They are working on federating with ActivityPub, and there are lots of clients for AP that can be used without JS. The default frontend for Pleroma (which is the AP server I run) has a JS free option.
I think there are already web clients that are meant to be run standalone and can connect to any server anyways though, so those might be useful for viewing Threads.
I think there are already web clients that are meant to be run standalone and can connect to any server anyways though, so those might be useful for viewing Threads.