Taildrop is just an extra feature tacked on top of Tailscale, it’s not a separate product. Normally each Tailscale node only does VPN tunneling, routing, and a bit of DNS. “Taildrop” is marketing speak for “now you can also transfers files between nodes”.
They also have a feature where Tailscale acts as a SSH server if you don’t already have one on that node. It’s called… get ready… Tailscale SSH. That one wasn’t a very exciting name.
But seriously, if it were easy they’d probably also add some sort of remote desktop, that would be really cool.