Should I just give up on snaps and use Flatpack or Appimage?

Use your system’s native package manager and repository unless you have a really good reason not to. Really good reasons include:

• Proprietary software that can experience library incompatibility and should be used inside a runtime
• You’re using something like Alpine Linux that uses musl libc and you want to install software that depends on glibc
• The software isn’t ported to your distribution (though the better solution would be to just write a package yourself)