CRDT at the very low level is an append only operations log with snapshots. This can be easily stored in a file. The trick is to solve merging with another version you just got from a friend. But then operations are idempotent and appending two operation logs with idempotent operations is simple.

Yes, ideally OS would provide a container that it natively merges, but meanwhile nothing prevents apps from storing their data in say sqlite based append only logs and when needing to solve conflict/import/merge just append new operations.