As for those people you say you need whatsapp for I would tell them all we ain't friends no more if you don't switch. Use Jitsi the open source self hosting voice/video conference chat with text chat in it as well. If you need a im app use matrix or simplex. Matrix has jitsi intergration so if you set them up you could voice/video chat with your friends within the matrix element app itself.
I don't like signal personally because requiring a phone number is a contradiction to the whole purpose & there is absolutely no nescessary need to require a phone number for private chatting it's just to help the government know whos using what.
The good thing about jitsi is it works right in the browser you don't need to download the app to use it. The app just gives you a history of rooms you joined. You can learn all about it from meet.jit.si but if you want to use it don't use it on the official site. The devs went contradickory harvey two face on everyone & made their official instance require third party logins after being bad mouthed online for being horrible support against nefarious users. This however does not affect the software itself so if you want to try it I would use another instance hosted by someone else like.
Room names are made with just url/name
like https://jitsi.4d2.org/thefunchat
Easy peasy isn't it?