Yeah, "app stores" are some new-fangled thing that was added in response to the Apple Mac app store.Most Linux users just use the main package repos which don't come with all that stuff.
ClipCascade looks like it does the universal clipboard thing.Available on Windows, Mac, Linux and Android (no iOS due to Apple restrictions).The server/relay component can be self-hosted too.
That price is the "volume price". Due to economies of scale, when you buy something in bulk it's usually much cheaper.
RethinkDNS also has all these features; as well as allowing multiple WireGuard VPNs running at the same time. It's an amazing app.
There's no "algorithm" on blog posts. You choose to subscribe to it or visit it regularly, if that's what you want.
You could always use Shamir's Secret Sharing (SSS) and distribute your password recovery amongst trusted but unrelated friends.
Perhaps, Fcast?