[thepete2]

I find the Markor app (open source) great for editing text files, you can also customize it quite a bit. Then for uploading possibly syncthing would work.

(I do this to sync my text files between my PC and phone, works great)

[RealStickman_]

I personally moved to Joplin and have it sync with my Nextcloud instance using webDAV. It's been working very well for me so far.