Are Sessions (stateful authentication) allowed in case of decoupled front and back ends?

I'm new to React, and I'm doing a project where the front and back ends are decoupled (chat application). The front end is a react SPA, the back end is a REST API (so to speak). I have a few questions:1) Do the front and back ends NEED to be completely decoupled in case of a client-side rendered application (e.g. React SPA), to the extent that I can not even consider sessions? Are there any actual problems that might arise, or is this just a case of "maintaining conventions"?2) Can there be some sort of middle ground where the front and back ends are largely decoupled (which to me means: client-side rendering, json communication between client and server, instead of actual UI), but not entirely? Like, SPA front end, API that sends only JSON (data), but sessions (stateful) are also used?Thanks.

Submitted September 05, 2020 at 08:19AM by NecroDeity