at least you could keep their reviews so users could at least know if the app can be trusted.

You mean, don’t trust a flatpak uploaded by a random person, but if there are enough fake reviews, it can be trusted?

I still think Ubuntu is the best option (particularly if you want to use the non-LTS releases)

Having said that I do hate snaps and also dislike flatpaks. So what I do is just use the Firefox deb package from the PPA and the chromium package from Linux Mint. Oh, and I have actually replaced ubuntu-advantage-tools with a no-op dummy package.

“secure alternative”? Others are not secure?