xn on Nostr: Right. Each relay can determine its own policies for who can post, what can be ...

Right.  Each relay can determine its own policies for who can post, what can be posted, how long posts are preserved, etc.


Running your own relay that only accepts your posts can serve as a backup that you could use to re-post to future relays.


https://github.com/metasikander/s0str is a relay designed for this use.