My MBA 2017 has a nice i7 that works for my use and could get a bit more life out of it if it had more RAM, as the model was only available from Apple with 8gb memory at the time. Getting 16gb to work would take past what it was made with, but as it it standard components, and Intel, it should work or?
I would get someone better at soldering than me to do it. :-D
Don't know about MBAs from that time. But the 16" 2017 MBP had been the worst Mac I ever owned in many cases. Keyboard (garbage from the beginning, Display ("Staingate" and "Flexgate"), Ports (2 of 4 unusable TB3 ports), Battery (completely dead from one day to another). For those I wouldn't recommend anything to invest.
Even my 2011 MBP with a GPU failure is running bettter.
But if the MBA is fine, why not, if possible for a reasonable price and you don't care about the latest and greatest software.
Edit: If you are from Europe and your country is available. I would recommend to have a look at the refurbed marketplace for a "new" device.
The .com-Link should redirect to your country's site automatically.
Der Online-Marktplatz für refurbished Handys, Laptops uvm. mit min. 12 Monaten Garantie. Refurbed Geräte sind bis zu 40 % günstiger und nachhaltiger als neu.
www.refurbed.com