which architecture is suitable for realtime chat application like what's app

I want to develop a real-time chat application in androids like what's app or telegram for the all-purpose client should connect to the server via WebSockets and even offline or online has to works fine I decided to use android architecture like MVP, MVVM, mvi but I'm confusing which one is suitable for my app may anyone help me to choose one of them? and my second question is it ok to use WebSockets for all APIs or it should better use WebSockets and rest APIs together? thanks for your help