They have shape tools on the roadmap for this free image manipulation app, until then we’ll have to use the two-step method of stroking a circular selection or use a more dedicated drawing app.
In any case GIMP 3.0 is a huge rewrite under the hood and seems to be attracting more contributors now, which is a good sign.
I would suggest avoidig pure rolling distros then. Also bear in mind that usually the performance difference between distros is not really big enough to make a difference for most things.
I would consider something like Mint. But what I did on my new laptop was that I installed PopOS 24.04 Alpha and used gnome-session (“sudo apt install gnome-session”) on it, though I’ve switched over to COSMIC now as I’m writing apps for it and it works for my games. It’ll get regular kernel+mesa updates but the base os will remain “LTS stable”.
You could also go the Fedora (KDE or GNOME spins) route, it has a regular update schedule, this might be a great option for you.