Specifically I could add a French door to a room to make it a bedroom.

Credit Karma uses a Vantage scoring model (which we do not use in the mortgage industry), but the trend will be the same as mortgage scores. 

I would ask, when you say real estate, specifically what are you trying to accomplish or do?

For commercial buildings, be very specific - price range, $/door max, unit count, unit mix, part of town.

All of this said, be sure to do your research on STR regulations first and find a STR friendly location.

Happy to help you as you have specific questions.

I have experience in single family fix and flip, 1-4 family rentals, small apartments (10-30 unit), 100+ unit apartments, development, commercial retail, industrial and office.

Not sure of specifics.

I'm eager to learn more about:Identifying undervalued properties: Are there any specific strategies or resources you recommend for finding deals below market value?

Check AirDNA for demand, pricing, etc.The Dekalb Board of Commissioners has proposed regulations for short-term rentals. https://engagedekalb.dekalbcountyga.gov/airbnb-dekalb-countyShort term rentals require you or your property manager to be hands-on and come with more risk.