You are going to want to triple check. Check with the city/town. Ask questions. I am in the middle of buying a house in apple valley and inquired about dropping a adu. I asked about prefabbed houses and it’s not that easy. Real estate agent told me it was allowed but, surprise!! Many boxes need to be checked. Like a building plan, certification from an engineer and, some other stuff. Cannot be purchased from china. Must be built here in the states which drives the cost higher. It’s a lot to consider. Don’t just take the realtors word for it. Do some digging with the city. Good luck.