“It’s a wildly heterogeneous collection of different databases,”
If employee data is involved, there should be SSNs, which could be handy as a key field in a relational database.
As for the other records, it’ll be a MESS.
People tried for years to redo entire systems. IBM was one of those to get a contract to replace one messed up system and the contract was eventually dropped. Just not possible. I’m betting IBM was more polite and cooperative with existing systems than Musk’s people will be. I see them as human steamrollers. Which is GOOD!