Rarely do I find software I need that’s not in the repo, but when I do, I just dusky build it myself. Not at my machine now, but I think I only have one PPA that’s not default added. In the other cases where I don’t want to build the app, it tends to be in Flatpak too.
That being said, although Mint is technically based on Ubuntu, it really doesn’t feel like it at all. I personally can’t stand Ubuntu, but again all personal opinions. If Debian-based systems didn’t work for you and an arch based distro did, then go with it. Everyone’s needs are their own and that’s why we have so many choices :D