I'll reply here as its probably the first place mega folks will find.
You can currently use Mega and its easy on the desktop (at least on Linux where I tried) - you just sync to the file system and sync to a folder in mega.
The harder bit is mobile sync. This is what I had to do:
- You need physical files on your mobile to use file system sync with. This can be handled using the FolderSync android app - it works really well and syncs with Mega
- I tried first syncing desktop joplin to mega and then syncing the mobile joplin with that but it fails
- The joplin mobile file system sync is a bit annoying because you have to know what the absolute path is which on android is
/storage/emulated/0/<YourJoplinFolder> - What I had to do was first get the mobile app syncing (I think it includes some extra hidden files) then sync this with FolderSync to mega and then sync this with the desktop Joplin
- Once that sync is setup, you can add other Joplin mobiles and desktops and they should work
This is still a bit of a pain though, I'd still rather have a mega provider. If I'm feeling enthusiastic one morning I might have a look what is required.