I think the key issue with notes that you just edit in plain text files on your computer is the lack of sync, mobile access and access to a quick ui on the mobile side.
Syncthing solves the markdown sync issue for me flawlessly on every platform. You can always use Dropbox or any other plain old file sync service too (OneDrive, NextCloud, etc.). At the end of the day it's just a bunch of files so you can use anything--sftp, rsync, xmodem over dialup... it's just files.
