Trillium is my personal choice for self-hosted notes. I haven’t really had issues with using it on mobile, but I also just tend to put the stuff I think of when I’m out and about into a single note that I periodically go through and reorganize. It’s been good to me so far, and it has all of the features I really need. If I need something fancier (or public-facing), I toss it in BookStack instead. Then again, I don’t use either of them for business (mostly for tabletop RPG stuff and instructions to friends/family about using the other stuff I self-host), so if that’s your application, I have no clue how it holds up.