I really like immutable distros, and am currently using NixOS. I feel like despite still being relatively obscure, NixOS is a bit of an outlier since it has more packages than any other distro and is (so far) the only distro I’ve used that has never broken. There is a steep learning curve, and I certainly wouldn’t recommend it for non programmers, but it is something truly different than all mainstream Linux distros while being extremely reliable.
Maybe Discourse? The mobile website is pretty good and there are also a number of third-party mobile apps.