On Amazon I was looking at the Camp Chef oven. It does not need to be mounted permanent and can be used in or out. It's portable and has an oven. I installed a propane converted apartment stove instead.......
https://www.amazon.com/Camp-Chef-Cam...ords=camp+chef
There is also the option of a 2 burner camping stove. Even smaller than the oven, but no oven. I have one to cook outside when it's hot.........
https://www.amazon.com/Coleman-20000...=coleman+stove
Microwave will require more juice. I don't think you need one. You need refrigeration. A 12V fridge will be a great option especially if you build your bus all 12V without the need of a 110V power inverter. There are many option like a cooler type 12V fridge or a trucker type fridge. Either way, a 12V fridge is great for a single person or a couple...........
https://www.amazon.com/SMETA-Lockabl...rds=12v+fridge
If you need more 110V appliances like a microwave, lighting, big fridge, computers, etc, then your power system inside the build will require constant shore power or a very large solar system, a huge power inverter, and large batter bank.