I really understand how hard is maintaining something for every single package manager and distributions
But for apps distributed in your system’s package manager, it’s not the devs that are distributing them in every package manager. It’s the distribution itself that goes to each repository, checks and tests the dependencies they need and creates the package for the distribution, along with a compiled binary.
When they aren’t offered in the distro’s package manager (or the version is outdated because the distro isn’t rolling release) things become more complicated indeed, and sometimes you can’t even do it because the dependencies are older than the ones you require.
If the distro is rolling release, it can always support the latest software in theory, you’d just need to have the correct package formula, which is exactly what AUR offers.
The problem with AUR is just that the author of the package is likely not the author of the software and not affiliated with the distro, so you should normally check what the script is doing.