You might check out nostr:npub17u5dneh8qjp43ecfxr6u5e9sjamsmxyuekrg2nlxrrk6nj9rsyrqywt4tp blog. I remember he had a post about building his own router. I don' remember how applicable it is!
Discussion
Not sure if OpenWRT runs on x86 but I found OPNSense rather user friendly.
Related: https://blog.lopp.net/how-to-protect-your-home-network-with-a-gigabit-vpn/
I enjoy OpenWRT on gl.inet hardware. They have great routers that already run on OpenWRT but you can kick their UI off completely if you want.