I actually use Obsidian on my Linux desktop, synced with Syncthing to my Android phone, iPad, home server, etc (have version control also active to keep older copies of notes). Mainly because the volume of notes I do is on the desktop, and I need them for reference everywhere. But I’m not sure Obsidian is best as a phone app (bit busy), but you could test it with a simple UI.
Interesting, I see Orgzly uses Org mode formatting in plain text - https://orgmode.org/features.html