I'm not sure if the new RRIO program covers this on the inspection, but I do know they look for illegal rental units (which the ADU would likely be considered if you don't live on property).  

As I'm looking to house hack and would love to take advantage of loan programs for first time home owners.

I've definitely seen the land academy system as well as Seth and Marks programs.

I know Ohio, I have found banks that offer less than 15% down for 2-4 units with smaller local banks or different programs like OHFA.

Rates will be a solid amount higher on this program and you will also have to pay points to acquire it. 

I'm not aware of any down payment assistance programs in the Bay Area that are not income capped, and that will go for 2-4 unit.

The benefit of a 30 year fixed loan program is the interest rate is fixed for the life of the loan.  

Although we do have some bank statement programs, it's almost always to think smarter not harder. 

I would suggest reaching out to both to see what programs would best suit your project. 

I've asked one apartment I'm interested in and they said they didn't know, that they used a program called Resident Check.