Regional banks and credit unions are generally the best places to look, and HELOCs vary greatly by lender... it's not like the Fannie/Freddy stuff where you jump through all these hoops to shave 0.125%, it'll be easily 0.75% or more of a spread between lenders. 

HiI am planning on building a ADU in Union City, CA .

I know military, VA loans, and real estate investing (duplexes are my speciality).  

Alternatively, you could put the money in a CD with any bank or credit union. 

I assume you would also recommend meeting with local banks and credit unions?

There are so many great areas like near the military bases, the Alamo, Downtown, Sea World, etc to invest in that I'm overwhelmed.

I'm trying to determine what a bank or credit union will give me.

As a busy military officer, I too know what it like not being able to attend many of these network events.

Do you rent mostly to military? 

I currently bank with a credit union, is that a good option to apply for a mortgage loan or should I branch out?