Pith
A Mac menu bar app that sends each app's connections out through the network interface you choose.
About
A Mac menu bar app for Apple silicon and macOS 13 or later, drawn with MyGo's native UI. Rules by app, domain or IP send new connections through Ethernet, Wi-Fi or a phone's hotspot, moving to the next interface when one fails, and Activity shows which interface each connection used. A helper installed with an administrator's password does the routing; nothing is decrypted.