I'm working on a Flatpak for SRB2Kart at https://gitlab.com/cbm755/org-srb2-SRB2Kart

Still need to work out a few things, but the goal is to post this to Flathub.org so GNU/Linux users can easily install it.

I'm no expert on Flatpak (this is only my second one) so I very much welcome help or feedback!

update: I found some help (or help found me) and work as moved on to https://github.com/flathub/flathub/pull/1526 so now its live at flathub.org and https://github.com/flathub/org.srb2.SRB2Kart