I despise ORMs. I don't judge programmers very often, but invariably if there is an ORM, there is a fragile, tightly coupled, difficult-to-maintain project nearby
That said, for microservice extraction specifically, a bit of creative metaprogramming/monkey patching of AR to identify & categorize your callers is probably easier.
the problem with activerecord is most people usually don't put this in place to begin with because the active record pattern makes it easy not to, which creates a massive pile of spaghetti code long term.