

Mint is basically Ubuntu with a lot of the questionable decisions fixed (and uses Cinnamon instead of Gnome, so it’s a bit more Windows like).
It doesn’t have snaps (though they provide instructions to add them if you want), it uses apt for packages and I believe pulls from a mixture of the Ubuntu repos and their own. It also has Flatpak out of the box and the software center does both, and clearly marks which you’re going to install with an easy drop down to switch if both are available.
Flatpak has been pretty solid for me overall, though there are occasional gotchas.
Honestly, I’d recommend going with Mint, pretty much anything that works with Ubuntu will work with it, and it’s better put together in my opinion (and doesn’t try to sell you a pro subscription by implying your system will be insecure if you don’t, which Ubuntu does). I know you’re not looking to switch, but I’ve honestly been very unimpressed with Ubuntu for the last, oh, decade or so
The problem is, Ubuntu from my understanding will try to install the snap version even if you explicitly are installing the deb version, including replacing a deb version with a snap when you update.
I’ve not experienced this personally as I stopped using Ubuntu before they started doing snaps, maybe they’ve gotten better about that, but I don’t trust a corpo run distro to not enshittify at every opportunity, so…