Can I turn my marinara sauce recipe into "pizza sauce"?

You will need to be careful about extra liquid in your sauce. Your base recipe should be adaptable. Go ahead and use the garlic and onion, but I would omit the white wine. If you are using canned whole tomatoes, drain liquid before using them. Simmer it to reduce it down until it is "spreadable" rather than "pour-able".

We make a lot of home-made pizza sauce with canned whole San Marzano tomatoes, drained and puree'd in blender. Salt, pepper, garlic and a few spices. My husband loves bright red color in the sauce so a bit of citric acid does the trick.

Enjoy your pizza.

You can absolutely do this. I tend to just use ground tomato with a little salt and pepper--sometimes cooked down, sometimes not. But really you can use any sauce that tastes good to you on a pizza.

If you're concerned about the sauce not being thick enough, I'd definitely suggest cooking it down some. Cook at a very low boil/fast simmer with the lid off. Use a wide, shallow pan if you can, as that will speed the cooking off of the water. Depending on how thick your sauce is to start, and how thick you want to end up, you may have trouble with scorching on the bottom of your pot, so watch your temperature carefully.

If you have plenty of time, you can pour your sauce on an edged tray and put it into a 225 degree F oven for a while to dehydrate/thicken. This takes quite a while, but the risk of burning/scorching is very low.

You can add thickening agents like starch, but the texture changes very significantly.

Add two or three times the quantity of onion you would use for pasta sauce, and cook them thoroughly. As well as thickening the sauce when you blend it will taste a lot more like pizza sauce. The only other essential is plenty of oregano.

Depending on the style of pizza you're going for, it might not take any effort at all.

Some pizzarias just use crushed tomatoes, and nothing more.

If I'm working from canned, I'll use whole peeled, slice then in half to remove most of the seeds, then crush them. When I'm using fresh, I just slice them and place them on the pie.

(then add garlic & herbs on top of the tomatoes, which gives you a chance to vary the amount for each person's tastes)

If you don't have time to cook it down enough for the pizza sauce consistency, try adding 1 can of tomato paste to it while you're cooking down. That is a "quick" trick for getting it right for pizza.

I find that crushed tomatoes work fine for pizza sauce. I dice 1 - 1.5 large Spanish onions, sautee with 3-4 cloves of garlic in olive oil until soft, then add a can of crushed tomatoes, some salt, oregano and some dried chili flakes. (I like a somewhat spicy sauce, so I often add extra garlic and/or chili flakes). Simmer off some of the extra liquid from the tomatoes, give everything a chance to break down, and you should be good to go. If you find that it's too thin for your taste, add extra onions or another vegetable like bell peppers and puree the whole thing.

Definitely avoid adding extra liquid (like your white wine).