To create rental income that enables financial freedom, you need a location that meets specific criteria.Rents increase faster than inflation: Prices and rents are driven by the imbalance between demand and supply.

The rental market is pretty rough here in the Austin area due to a glut of supply.

Housing supply is the other function, and my view as rates increase so does inventory in markets that are coming up to pre-pandemic levels and the inverse in the one's that are decreasing. 

I keep hearing that costs of labor and supplies are rising (when aren't they?)

It would be nice if you had a contact who was an actual mason not a marketer.  1930's construction is rare so maybe they cut some corners it was a global depression.  

There’s just not enough ADU supply (IN MY AREA) for appraisers to base off of.

If you don't flip, these guys are usually in the appropriate isles at Home Depot with the carts of supplies or just hang around the commercial check out.

The country simply does not have enough affordable housing units, and the new supply of affordable housing units is not keeping up with new demand.

Supply and Demand: When buyers outnumber sellers, prices and rents rise.Population Growth: Cities with significant and sustained population increases are more likely to see long-term rent growth.Job Stability and GrowthA property’s value is tied to the jobs in the area.

As Mitch pointed to, on one hand, STRs are housing supply locally and will likely get looked at.