Yep, but the awesomeness of ConnectRPC is that you can use the JSON api in the web browser, and indeed I do that in this project. We don't have to, and as a matter of fact it's a little less performant, but it's easier to debug and hack.
[meta: IMHO this is an exemplary HN interaction; instead of shouting past each other, we shared very different points of view, and one of us learned something potentially useful.]
Any idea how monstrous migrating from gRPC to ConnectRPC might be, on the backend?
https://connectrpc.com/docs/go/grpc-compatibility/
It might not be super simple. Good interaction, I agree :)
TLDR: there should be no migration cost.