This is very cool.
A way that I used to do this was through Owncloud/Nextcloud which was hosted on a Raspberry-Pi. They had a dedicated plug-in for this, and an app called QOwn-Notes.
But I also have an app called Notes-Up that stores all of your notes as single database file, and so if you keep that database in a Nextcloud, Google Drive, etc it's just that single file being updated.
There are risks too of course because if it gets wiped on one computer it will get wiped on others, but you could do a cron-job duplicate of it as well.