Grpc web limitations

I vent: Im trying to make a simple program (chatroulette like) with go server and flutter web client, using grpc apis, but I found some problems when the grpc gateway try to decode the json from the client, p.s. i don't know dart, but seems java :| And with this, and also all the problems related to the web standards (http 1.1, cors), I would like to expose the disappointment on the web world
https://github.com/LorenzoTinfena/chat-and-meet-client
https://github.com/LorenzoTinfena/chat-and-meet-server