Hi Adam. FHA applies for all 2-4 unit properties. However, the Self-Sufficiency Test (SST) only applies for 3 and 4 units (not 2) so this can kill a lot of 3 and 4 unit FHA deals. The SST requires 75% of in-place rents (or market rents for units that are vacant or month to month) to be greater than your monthly PITI payment (principal, interest, PMI, Tax, and insurance). For relatively expensive markets, like Phoenix, this can be difficult to pass as the rent to price ratios of many properties are very low. This makes it hard to find a property with rents high enough to cover the PITI.
However, since 2 unit properties do not require the SST they can oftentimes be far easier. Just make sure you know the counties FHA loan limits on a 2-unit property.
I just looked up Phoenix loan limits and they are: 1-unit = $368k, 2-unit = $471.1k, 3-unit = $569.5k, and 4-unit = $707.7k.
So if you want to put exactly 3.5% down on a 2-unit property you would need to find a property for $488.19k or less. However, you can always just bring a little more money down and still qualify for the low-money down loan product.
Once again, I do not know the PHX market very well but in more expensive areas like the one you are looking in, you oftentimes need to adjust your goals to be more "House Hacking for the purpose of paying lower rent" as opposed to "House Hacking to pay no rent or even cash flow". At the end of the day, if you're house hacking and paying $500 per month as opposed to renting for $1,000 you're still saving a lot of money and also building ton's of equity in loan amortization and hopefully appreciation as well.