which distro to go with? I want one that "just works" without having to scour the net to get WiFi drivers etc.
I tried Linux Mint (2 diff versions) and Xubuntu (3 diff versions), yes, *versions might matter.
Try as
@doctor_dog suggest, USB drives or USB hdd first, so you can check if all your hardware works out of the box. I didn't have any issues and everything just worked. In my experience, Linux Mint (v20 I think) was the fastest to boot and fastest for random use, web browsing was very fast. In my case used a PC to install the full OS on the hdd and then placed it in side the mac, worked just fine. I just didn't like using Bootcamp to do it.
I mentioned versions being of certain importance because not all Linux versions are the same. Since version... 22? I don't remember, your installation uses GPT out of the box without even telling you, this caused me issues, but using previous versions worked just fine and Linux got installed as MBR (out of the box, and allowed me to choose too).
*except for changing display baklight (need the nvidia driver for that AFAIK).
Yes, sort of (depends on the case). Ubuntu and Xubuntu "didn't" work with the backlight, but Linux Mint worked perfectly out of the box. There are 2 main aspects here. Linux will set by default the generic video drivers known as Nouveau, these work pretty well!!!!, but the video acceleration for playing video is not using all the power of the GPU. You can switch to the official Nvidia drivers using an option on the os ("additional drivers"), then you will have full acceleration but it might break some things. In my case, the best overall experience happened with the Nouveau drivers. A couple of Linux installs allowed me to choose from 3 options, others from only 2.
I said Xubuntu "didn't" work with the backlight because out of the box there is a slight detail missing. See, using Mint everything worked, but Xubuntu didn't respond to brightness changes. Turns out you HAVE to add a widget to the menu (the panel), specifically "brightness control", and this will let you use a fancy slider to adjust the brightness, try it.
Multiboot can be a bit technical for most people, proceed with patience. Or explore Ventoy (this is what I use on my iMac), my wife uses Windows on her MBP. Back to Ventoy, you can boot multiple operative systems (isos), or if you have patience to create VHD files (virtual machine hard drives), then it's an option too, that's what I use.
As for specific virtual machine software under Linux, there are tutorials about running MacOS inside Linux pretty damn fast, one of them is Sosumi (there is another one but can't remember the name), while this worked for lots of people, sadly didn't work for me.