Undocumented restriction to lightning experience only?

Sorry for asking this in the example repo, I wasn't sure where to get clarification - here or in the lwc repo - but given it feels like a documentation gap, I thought I'd start here!

I've attempted to use @lwc/state in Experience Cloud in a preview org (LWR build-your-own), and the module is returning 404. I'm not sure if it's because I need to set a flag to opt into the beta, or because of lightning locker, or just because the module is not available in the LWR runtime.

My hunch is the latter, that @lwc/state is lightning-experience only at the moment?

No files, tests, or entry points are named. Start by confirming whether @lwc/state is available in Experience Cloud LWR and whether an opt-in flag or runtime restriction explains the 404. Done means documenting the supported environments and any required configuration, or directing the question to the appropriate repository.

Written by the indexing model from the issue text.