But then, your firewall or Cosmos is exposed to the internet waiting for a 0day to be released, and chances here they will not be updated as soon as it comes ou

But then, your firewall or Cosmos is exposed to the internet waiting for a 0day to be released, and chances here they will not be updated as soon as it comes out. VPN server is already what Tailscale does at this point. I'm not a shill by the way, just a regular user impressed by the ease of installation/use of their product.