They are great, I use InputLeap regularly. But the things mentioned in the post transfer video as well, which is a different use case. The synergy family of tools allows to share input devices with another machine, but not use it as a second screen for software on the first system. Depending on the goal, one can work around that with network file systems and having the same software installed on both PCs.

Well, having a domain is basically documenting your IP publicly. It’s not that risky.