He found a home that he loves in Texas but can’t get approved for a VA loan because he only has his pension as income. 

I had moved more than 50 miles because of work and my FHA loan had a clause where I was automatically approved to buy a house with 3% down in that scenario.

I am open to an FHA loan or house hacking and living in one of the units.

I would try first seller financing, then a bank loan, and then cash.

Is it a conventional loan or something else?  

Use a 5% down conventional loan.

I would like to continue this way, with a maximum of 10 loans taken at any given time.

Today it will be very challenging as the rates on HELOC’s will be very high.Unless you perform the labor or get a screaming deal, your chances of getting all your money out will be challenging and it may end up being near 100% financing and thus little to no cash flowNot saying it cannot be done but in high interest rate environment brrr makes it that much harder

Our bank will allow us to keep the best loan.  

I've been in mortgages since 2019, and since I only do DSCR loans, I don't bother marketing to California because cash flow is non-existent.$800k for a duplex is already ridiculous, but the cherry on top is $4,100 rent.