I used beeper for that because it enables you to choose between hosting the bridge on their server, hosting the bridge on your computer but using their homeserver which makes things way easier or just using the on device bridge in their app with no server (except iMessage because apple immediately patched every attempt of theirs so now you need a Mac to bridge it)
The WhatsApp issue that you have to open the original app every few days is unavoidable sadly.
I used beeper for that because it enables you to choose between hosting the bridge on their server, hosting the bridge on your computer but using their homeserver which makes things way easier or just using the on device bridge in their app with no server (except iMessage because apple immediately patched every attempt of theirs so now you need a Mac to bridge it)
The WhatsApp issue that you have to open the original app every few days is unavoidable sadly.