Pacstall is AUR for Ubuntu (so UUR?) based distributions.
It is certainly less complete than AUR, but still it might be useful depending on your needs.
I'd rather trust an Ubuntu community repo than the snap store. At least, for pacstall, the community is able to review the package.
Since the snap store is the default store on Ubuntu , there is more chance that he will be targeted by malicious software than a community repo than has to be manually installed.