They do exist.

As others stated, if the existing structure is legal but non-confirming that should not be an issue.

SBA loans can also be used to purchase existing real estate, as long as at least 51% of the square footage is owner occupied (so occupied by your business). 

Saika  While a permit is a hassle, what happens if there was a fire, it burned down, someone got killed and the fire department was not even aware the unpermitted structure existed.

How much "fat" do you believe still exists within that? 

You can do this with a simple, one-page addendum, or even a written statement added to the existing lease and signed by you and the tenant.Example:This lease agreement is hereby amended to reflect the change in ownership of the rental property located at 123 Straight Street, Cody, WY 82414.

Are you taking this subject to existing mortgage?

 I'm not opposed to subject to, but my fear is whoever I am taking over the existing mortgage from will not continue making the payments.You make the payments.

Let me know if you have an existing group or interested in forming one in 2025.  

This amounts to lost opportunity because if you had purchased RE, at the closing it can start producing return. 5) ADUs detract from the existing structure whether this is privacy, a garage, or just yard space. 6) this is related to number 1, but there are many more buyers looking to purchase homes for their family than there are RE investors looking to purchase small unit count properties.