Sampling wrappers were already implemented a while ago, but so far only reloo uses them. If you are interested and available I’d be happy to help ypu implement that and review your PRs.
You can take a look at the current sampling wrappers example using reloo to get a feel of how they work (still not updated to pymc v4 though): Refitting PyMC3 models with ArviZ — ArviZ dev documentation