Sure, as long as the VPN itself is secure. Strong passwords/keys, etc. A VPN itself can be a potential security risk, as if it’s compromised an attacker can tunnel traffic directly into a network straight past a firewall.
The risks can definitely be mitigated, but if someone’s asking for an ELI5 on KVMs, then it may be best to stay away until they have a better understanding of IT infrastructure altogether.
Both kinda already exist.
Easier to control for variables with airplanes. It seems like a simpler (still hells difficult, but simpler) problem to solve, so them first I’d guess