Nor is there a permit to do so. 

Check your local (city) municode to see applicable zoning rules/permitted uses.

I would keep reaching out  (emailing is preferred, so it's in writing) to the county permitting department until you get a clear answer, even if it is "We don't have any occupancy septic rule". 

It wasn't and we had it permitted.

Hi,I have a permit to build a 720SF ADU in Oakland.

[Realtor.com]Starts & Permits: Long-term PerspectiveHousing starts disappointed in July 2024, falling 7% month-over-month to 1.24 million units (SAAR).

Realistic timeline 6mo not including permitting.

Is the city issuing new permits? 

I’m aware of permit requirements in my local township, and I would have to follow up with what’s required in the location of the investment property. 

Furthermore the local experts can confirm the following: (1) the use is allowed, (2) the use requirements can be protected by permitting and licensing and (3) the permissions are transferable through a sale.