NGINX solves half of the problem. It allows accessing UNIX socket services over TCP. This is great and I do it wherever possible (mostly because I can add my ow

NGINX solves half of the problem. It allows accessing UNIX socket services over TCP. This is great and I do it wherever possible (mostly because I can add my own access control and everything has to go through it, even local processes). But it doesn't allow local access without going over TCP. So for example if CUPS or Syncthing listened on a UNIX socket you can use NGINX to expose this over TCP, but now you are back at the original problem of any local process can access this service and you need to worry about port conflicts. You can work around this by adding access control but this doesn't elegantly solve the core problem. So it is valuable to have a client (like Firefox) that can directly access the socket. This way you get native UNIX permissions and a whole filesystem namespace to prevent conflicts.