When I had a Mac I used an encrypted volume in Dropbox. (Not sure if that's a good idea, but I didn't have any issues.)

I used Notational Velocity in those days :) A rare gem of ergonomics.

Later I did the same thing with a VeraCrypt volume.

Now I'm in Obsidian, which has its own encryption (if you trust 'em!), but never quite got the frictionless feeling of NV back.