No worries thats cool and a great contribution. (didnt mean to attack your work).
i have only used gluetun in a docker like context so i cant honestly tell you but you can have vpn and non vpn traffic on your system and you just proxy traffic.
also, now i can see the reason for this (work) and why its cool, which was missing in your post. Also knowing your approach helps others point you to ways to improve what youve done. Thanks you!