Some loan officers can comment more on those.

How can a 20th-year-old approach commercial loan officers and investors to lend the money to invest in a 8 or 10-unit apartment?

@Maria Murphy yes correct, simply paying the debt in the owner's name to hacienda (tax office)/government first as part of the purchase at the notary and everything left to the seller.Valencia has worked quite well for us the last years and compared to Barcelona/Madrid the m2 prices are a lot lower.

Aside from the responses above regarding the bank likely requiring the 20% funds to be yours, good luck finding any private lender willing to take a second position note on a 100% LTV for any %, let alone a tiny 3%.Now, banks do, at times, allow seller carried back seconds, but unlikely with no skin in the game from the borrower.

Meet with the title officer and ask them for a short list of investors who actually buy.   

Our office is just outside downtown.

What I see is that they in single family zoned areas they often will convert other living space (craft rooms, offices, finished wood shops, etc) to ADUs but do not convert garages.  

Using a VA loan for a second property, where I’d move in and rent out my current home.When I made an offer on a fixer-upper (I didn’t win that bid), the loan officer mentioned it might be difficult to convince the underwriter why I’d need another VA loan for a second property in the same area, especially since the new home is almost identical to my current one (same size, age, school district, etc.).

It provides links to each county office's sites for when you're doing research. 

Or we could build office buildings there and lease.