What conversions are "easy" to get approved for a garage?

[Jon Vert]

I'm buying a house in Los Angeles which has a garage that was converted to a guesthouse (i.e. it has nice finished floors, no garage door, a bathroom with toilet/sink/shower and kitchenette with sink/electric stovetop).

From a risk perspective, I'm (relatively) ok with this, particularly because the entire home, garage included has been inspected many times (with no issues) as a new Certificate of Occupancy is being issued.  It's unclear to me why the inspectors have made no comments whatsoever about the garage - the seller says it's because no existing plumbing or electrical was changed.  As far as I can tell, the structure was previously permitted (in the 80s) as a "garage + workshop."

I'm just trying to figure out what is allowed to be in the garage by default, or what could be permitted. It seems as though the kitchen is the least likely thing, followed by the shower. However I've been told that getting a "rec room" permit should be no problem and that would allow the toilet, sink, and lack of garage door to remain. From what I can tell, we *cannot* get the garage permitted as an ADU because power lines run almost directly above it. We have no desire to rent out the structure and intend for it to be "mixed-use" - i.e. storage, playroom, game room, occasional guest room, etc.

I think my main question is this (though any other general opinions are very welcome):  If the city comes to us and complains, I assume we'll have to remove the stove, and possibly the shower.  But then what is the likelihood of getting some kind of permit (e.g. for a rec room - is that even an "official" thing?) that would allow us to keep the toilet, sink(s), and not require us to install a garage door?

Thanks!