For your multiple-device problem, I would suggest trying Syncthing. It allows you keep folders synced between devices over a local network. I use it for a very similar application to what you are describing:

Logsec is a journal/note-taking software that stores each entry as it's own markdown file. I use it on my phone, laptop and desktop, and want to have all my notes synced between devices. I could put the folder of markdown files on a cloud server, but choose not to. Instead, I setup a link between each device's Logsec folder through Syncthing.

Now I can add or update notes on my phone when out in public, and when I return home and reconnect to my WiFi it automatically updates the other devices on the network. Also, when editing the markdown files on my desktop, the updates are synced to my phone nearly instantaneously.

I expect this method would work very well with Scuttlebutt due to it's similar offline nature.