If they won't have it then they're not microservices. The main premise is independent deployability. You need to be able to work on microservice independently

If they won't have it then they're not microservices. The main premise is independent deployability. You need to be able to work on microservice independently of the rest, deploy it independently, it has to support partial rollouts (ie. half of replicas on version X and half on version Y), rollbacks including partial rollbacks etc. You could stretch it in some kind of quasimodo to have separate schemas within single database for each microservice where each would be responsible for managing migrations of that schema and you'd employ some kind of policy of isolation. You pretty much wouldn't be able to use anything from other schemas as that would almost always violate those principles making the whole thing just unnecessary complexity at best. Overall it would be a stretch and a weird one. Of course it implies that before simple few liners in sql with transaction isolation/atomicity now become phd-level-like, complex, distributed problems to solve with sagas, two phase commits, do+undo actions, complex error handling because comms can break at arbitrary places, performance cam be a problem, ordering of events, you don't have immediate consistency anymore, you have to switch to eventual consistency, very likely have to do some form of event sourcing, duplicate data in multiple places, think about forward and backward compatibility a lot ie. on event schema, taking care of apis and their compatibility contracts, choosing well orchestration vs choreography etc. You want to employ those kind of techniques not for fun but because you simply have to, you have no other choice - ie. you have hundreds or thousands of developers, scale at hundreds or thousands of servers etc. It's also worth mentioning that you can have independent deployability with services/platforms as well - if they're conceptually distinct and have relatively low api surface, they are potentially extractable, you can form dedicated team around them etc.