Tailscale negotiates a direct VPN to the VPS and all traffic going through the VPN goes through the VPS.
As for bandwidth its not really that expensive unless you need like 30-50tb per month type numbers.
If its specific machines you can install tailscale on those also and they make a direct connection.
I got on my phone,laptop,tablet etc so wherever i am it will use tailscale as middleman to find open ports and establish a vpn to home network.
This part is often overlooked for sure.
If planing on running it for a while picking up a pair of lower wattage psus will often recoup its cost + help reduce noise.