it's a good, but tough, market to invest in.

What are the closest markets where it is still legal?

Look at their marketing strategy.

This means researching the market, understanding tenant demand, and ensuring the cash flow comfortably covers the loan payments.

Every time we build a new home, we add more supply to the market.

In this market that's hard to find cash flow, I'd offer to look into a live-in-flip to get your feet wet & a solid understanding of rehab costs. 

I found an off-market duplex with ADU that is non-conforming, and I would love to buy it to rehab it (keeping all 3 units).

If you want to network or ask specific questions about your local market, go to your local real estate forum and connect with investors from your area: https://www.biggerpockets.com/forums/86-local-real-estate-networking5.

Obviously, the burbs out past 465 can be good appreciation markets. 

I also help other investors get started there with my team.It's a great market but you really need to understand the landscape and risks.