How do you route all a host system's traffic through Gluetun? If you use routing tables, wouldn't it similarly be affected by TunnelVision? In which case you would still need a firewall on the host...
Also, the host system likely makes network requests right after boot, before a Gluetun container has time to start. How do you make sure those don't leak?
I am curious though, how you were able to route all host traffic through Gluetun. I know it can be used as a http/socks proxy, but I only know of ways to configure your browser to use that. What about other applications and system-level services? What about other kinds of traffic, like ssh?