This would be the killer 2050 alien feature. Git is a really good mental model on itself. Git + Neon = you invent the future!
Doing so for a database seems less desirable from an availability perspective, especially with high-throughput databases.
But, because SQL has conflict resolution by cancellation of one of the two conflicting modifications, I don't think that it is reasonable (or even possible) to merge 2 divergent databases in a single way that always conforms to the needs of the developer and/or application.