wacom-gui VS mate-optimus

Lastly, I was just looking at the Arch Wiki (which I recommend no matter what distribution you use, it has a lot of good information) and came across this: "wacom-gui" (https://github.com/tb2097/wacom-gui) that might be worth a look.

You might check out https://github.com/tb2097/wacom-gui which is for desktops like XFCE which don't have a native Wacom control panel. I've run into a few problems with it in the past (it was having trouble remembering settings), but things may have changed and it might work better for you.

when I started out, I used red hat, Suse linux, and then finally I jumped to Ubuntu, when they killed gnome and rolled out their new GUI later, I switched to Ubuntu Mate, with xfce alternatively installed. And then later came MINT. which is based on ubuntu anyway.

Prepare a blank USB stick with a copy of Ubuntu (write the ISO to the USB stick with Rufus)

Ubuntu MATE (simple, well maintained, has the Ubuntu ecosystem support and should work well)

Linux Mint has its advantages, but your title doesn't make sense when there's Ubuntu MATE.

(btw: since the PC is older I would reccommend Ubuntu Mate or Xubuntu as those come with a lighter Desktop)

You can always change desktops later to Cinnamon or MATE or XFCE. If you want to try those desktops on your USB drive, you can download Ubuntu MATE or Xubuntu and try them on USB, just like you're currently doing.

My experience has been that Ubuntu's Gnome DE is somewhat less suitable to older computers than Ubuntu "official flavors" with lighter DE's -- Ubuntu Budgie (Budgie DE), Kubuntu (KDE Plasma DE), Ubuntu MATE (MATE DE), and Xubuntu (XFCE DE) -- all of which use somewhat less resources than the Gnome DE.

Consider looking at several of the Ubuntu official flavors -- Kubuntu (Plasma DE), Ubuntu Budgie (Budgie DE), Xubuntu (XFCE), Ubuntu MATE (MATE DE). I wouldn't bother with Lubuntu (LXQT DE) unless you need a lightweight distro, because the LXQT DE is not as mainstream or well-supported as the others.

Based on recent experience helping a handful of friends move from Windows to Linux, I suggest starting with an official Ubuntu flavor (Ubuntu Budgie, Kubuntu, Xbuntu, Ubuntu Mate) 22.04 LTS release, picking which ever desktop environment appeals to you. Official Ubuntu flavors are the Ubuntu OS layer with standard but different desktop environments.