They are not as restrictive as people make them out to be. Ostree works quite well for installing a primary app like a different browser.

If you want to avoid dependency conflicts entirely, You can have a look at distro shelf. It allows you to run a container for nearly any distro, install packages and then export those apps to run like native apps. I use it all the time when something is only supported via package and not flatpack, or some other distro only.

The container still maps to your same home folder for file and config access.

I have 3 containers, a fedora workstation one for standard apps I don't want to do via Flatpak or AppImage. An Debian one for deb packages. And lastly a Arch one, which is for the more experimental apps. If I end up breaking something, I can just wipe the container and start again.