Ahh.. so you want to only sync locally between devices.. or you want it to support your special cloud-protocol so you can run your own cloud-server... . But wouldn't the second part be cheating, not naming it cloud-based?
Non-cloud as not chained to the provider's storage services, I want to decide how to sync it between my devices. I want a tool for my notes, not SaaS. I wouldn't mind paying for my tool chain, what I wouldn't want is paying rent for my own notes.
Syncthing with Wireguard/Tailscale is not exactly local, not really "cloud".
As long as you have two connectable devices Syncthing doesn't have to be strictly local. It'll take advantage of local networks, but it's certainly not limited to that.