I am seeking a solution that will enable me to mirror the screen from Android (LineageOS 20) to Android TV (LineageOS 20 for Android TV). Chromecast is only accessible for Google-certified devices; therefore, Chromecast will not function here.
Is there a project in which I can install the receiver app on the Android TV and the client app on the Android phone to accomplish this?
If all that mattered was being on the same network, it doesn’t matter whether that’s WiFi or Ethernet. Frames got switched between those.
WiFi Direct uses, as the same implies, a direct P2P network between the two devices without a third network device in between.
That would indeed not work if the device has no WiFi adapter.
You may perhaps be able to remedy that using a USB WiFi adapter supported by the mainline Linux kernel version running on your device.
Have you tried it though? I’m pretty sure Miracast works over the network too.