My view on exosomes is more cautious than most. For me, it seems a bit of a stretch to suggest that "exosomes" replicate. I think they are just structures like "antibodies" ... which emerge when cleanup is required and which disappear when they are not required.

EXOSOMES likely use "signalling" to communicate garbage pickup, but other functions attributed to them is beyond my purview to comment on.

IMO, the notion of virus replication was advanced to legitimize virus theory, e.g. to create the prospect of a problem doubling itself indefinitely.