One interesting issue is that as the number of devices rises, the effort required to pair them all together rises as O(n^2) rather than O(n). With Dropbox, you can add all your devices into an account and they'll all share a folder, but on Syncthing you have to add every device to every other device, unless you have a central server (here a laptop I never sleep), set it as an introducer on every other device, then by adding a new device to the server it gets pushed to all other devices connected to the server. KDE Connect, unlike Tailscale, has the O(n^2) problem if you want to pair every device with every other device. I'm not sure the best way out; KDE Connect shouldn't require a central authority like Tailscale's management servers, perhaps a LAN server, or an optional integration to publish keys on Tailscale and auto-pair with keys available there? But is it secure to allow one device to connect to your account and add its keys to all your networked machines? Then again Syncthing introducers already do that, but Syncthing doesn't offer remote code execution while KDE Connect can emulate a keyboard.