Probably not a concern as I recall the TC said she wanted to only play older games (not sure how we're defining old though). The build I linked has an 8GB Nvidia GPU which is already on par with the PS5/XSX so this should last for some time, especially considering that there isn't a target resolution in mind. I'm assuming the monitor being used is a 1080p monitor.
Older games, but newer graphical design (both 2d and 3d) programs. I can install my own RAM cards if I have to (I already know the rule is both cards must have the same memory capacity)
Mint is going to have really old Nvidia drivers and a host of other things. Honestly I would avoid anything Debian based on a desktop besides PikaOS, which has a ton of hand maintained packages to bring things up to date.
Mint was what I gave as an example. I already figured that it wasn't something I would liter
On hardware, I will just say avoid prebuilts. Theyre goin to have garbage RAM and motherboards most of the time. You can use a build service like NZXT BLD to build a PC for you, or ecollegepc, etc.
I don't know if I have one of those close to where I live, though.