Substitute in home made pizza sauce?

You can, however, salsa is already seasoned, you would only use that rather than the rest of the ingredients. The taste wouldn't be anything like a traditional pizza sauce. I would drain it if there is an excessive amount of liquid, whiz in the blender and top with browned hamburger seasoned with taco seasoning, then top with cheddar and sliced black olives. Bake it off, remove from the oven and top with shredded lettuce, diced tomato and a dollop of sour cream. Viola! a mexican pizza. I have done this before and it's quite good.