Like many here, I have lived in a mixed OS environment for decades: Windows at work, Mac at home.
Last year, I added a cheap $170 Wintel PC (Mac mini form factor) at home to function primarily as an old school home theater PC but also to host legacy applications that are endangered on the Mac in the post-Mojave 64-bit only world. While Kodi functioned on the Wintel cheapo, the fan kicked in rather frequently. About a month ago, I got a $99 Raspberry Pi 4 starter kit and am now running Kodi silently in a LibreELEC instance. The Wintel cheapo still is useful in running my brokerage's trading tool (it's a Windows executable) on my living room's big screen TV.
My regular desktop is a Mac mini 2018. I am interested in dabbling with Davinci Resolve so I acquired a Sonnet eGFX Breakaway Box 550 and a Sapphire Pulse Radeon RX 580 8GB graphics card, an approved combination in an official Apple support document. It works pretty well in the limited time I've had to play with it. The eGPU combo also works with my MacBook Air 2019 but I never use it with the notebook since it doesn't give me anything that my Mac mini 2018 won't offer.
However, I had been eyeing Windows PCs with Thunderbolt 3 for a while (including Intel NUCs which don't appear to be a good value) and saw that reasonably priced TB3-equipped notebooks with 10th generation Intel CPUs started showing up in the market.
I ordered this Acer Swift 3 (model SF314-57-59EY), 10th-gen Core i5, 14" HD screen:
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which retails for US$680 (sales tax not included) and mentioned TB3 in the specs. I was skeptical at best (comments by Amazon customers ignored TB3) but figured that if TB3 did not live up, I could return the unit. Acer also sells Swift 3 models with AMD Ryzen CPUs but I wanted the Thunderbolt 3 functionality.
This Acer Swift 3 is comparable to the MacBook Air 2020 (I have the 2019 model). It's slightly lighter, a little wider (maybe a quarter of an inch) than the Air. The MBA has a better screen: 220 ppi Retina Display (effective 1280x800) vs. 170 ppi HD screen (actual 1920x1080) on the Acer. I really don't care much for the Swift's keyboard; the Swift's trackpad is absolute garbage. The Acer's fingerprint biometric login device is less accurate than Apple's Touch ID.
Both have Intel's wimpy integrated graphics and claim the same general battery performance (10-11 hours). The Acer Swift's fan is quieter than the Air 2019's. The Acer is slightly thicker than the Air, but it also accommodates one USB 3.1 A port, one USB 2.0 A port and an HDMI connector built-in so less money spent on dongles.
After the usual dreary Windows system administration (a bunch of OS patches and device driver updates plus the usual bloatware removal) I ended up with an up-to-date Windows 10 version 1903 installation which various sites and articles claimed was the first Windows 10 version to provide ample TB3/eGPU support. I plugged in the eGPU and in a few seconds the Acer Swift mirrored the screen on the 27" LG 4K monitor plugged into the eGPU via DisplayPort. I found the Intel Thunderbolt app in the Windows Store then proceeded to mount the ATI Radeon software installation CD that was included with the card. To my delight, the CD software recognized the RX 580 GPU and proceeded to install the ATI Radeon Adrenalin 2019 driver & utility software.
From there, I subsequently upgraded Windows 10 to version 1909 and installed the latest and greatest ATI Radeon Adrenalin 2020 software. While I'm not a gamer, I downloaded a couple of freebies from Epic (Fortnite) and Blizzard/Battle.net (Heroes of the Storm) and fired them up. The Acer Swift 3 + Thunderbolt 3 eGPU combo appears to be legit for a casual/infrequent gamer like me.
I do like flight simulators and perhaps I'll find a way to commit a bunch of FAA violations like skimming Manhattan's Fifth Avenue 100 ft. above street level, flying under the Golden Gate Bridge, dive bombing football stadiums (empty of course) or screwing around in the Grand Canyon.

I figure a high-end gaming rig isn't necessary to do that.
A fancy Razer gaming notebook PC will presumably beat up my Acer Swift quite handily but for someone who might be in the same situation this Swift 3 provides Wintel mobile productivity on the road with decent battery performance while being able to take advantage of an eGPU's graphics muscle at home.
Cost comparison? My MacBook Air 2019 (upgraded 8th-gen i5, 16GB RAM, 512GB SSD) was $1650 (incl. tax) when I bought it about a year ago. The Acer Swift 3 (10th-gen i5, 8GB RAM, 256GB SSD, Windows 10 Home) was about $745 (incl. tax) and the eGPU (Sonnet box + Sapphire card) was another $465 (incl. tax), total $1210. So for $440 less, I have a Wintel notebook setup that blows doors on the MacBook Air in 3D graphics performance. Plus I can share that eGPU with the Mac mini 2018.
I could shove in an even better card like the Sapphire NITRO+ RX 5700 XT 8GB and still have a hundred bucks in savings. I am actually debating whether or not to do just that: send the Pulse RX 580 and upgrade within the return window.
In a couple of weeks if all is fine, I may ditch my MacBook Air as well as Windows virtual machines on both my Air and Mac mini to reduce total system administration load. Excluding my cheapo Wintel box, rather than running five OS environments (3 Win10 + 2 macOS) on three machines (1 Wintel + 2 Macs), I can just run one W10 + one macOS each on respective machines.
Total Cost of Ownership? Here is where the bargain value of Windows hardware starts to erode. Based on 18+ years of Mac notebook ownership, I would expect the MacBook Air to provide 5 years of service (based on my usage case). The $1650 sticker price works out to $0.90/day. I would expect about 3 years of service from my cheapo Acer Swift 3 ($745), about $0.68/day.
Software value? Macs include the free iWorks suite (Pages, Numbers, Keynote) as well as the free iLife suite (iTunes/Apple Music, Photos, iMovie, GarageBand). Some of these have direct freeware Windows equivalents, some do not.
The main caveat is that I would be stuck running Windows 10 on the road. That's okay for me, I don't use notebook computers that much anyhow. Most of what I need to get done on the road can be done with my iPhone and/or moldy old iPad mini. I've installed iCloud for Windows on the Acer Swift for file sharing/web browser bookmarks with my Mac mini. Thunderbird is my e-mail client of choice on the Windows notebook. It isn't pretty but it works. Of course, having a Wintel PC opens up a much larger universe of applications, games, etc.
In the end, much of this comes down to each person's specific usage case. The things I need to do when I'm on the road are a minor subset of what I do at home. There isn't really much on the road that requires macOS-specific applications for me. I can even stream my personal music library (mostly ripped classical CDs) on iTunes since I have iTunes Match.
Anyhow, food for thought for those who can live with modest Wintel performance on the road (3D gameplay will be crippled on Intel Integrated Graphics) but who seek more robust 3D capabilities at home and wish to share enhanced performance with Macs.