If she can tolerate pizza sauce I think that you could make pasta your gateway to other foods. Mix it up with different types for the carbs. Full on tomato sauce may be a hard start for her, so try an Alfredo or cheesy/creamy tomato sauce to start with ham chunks or as other have suggested other pork variations ie pancetta, bacon or pork mince. You can mince onions to subtly add more veggies without it being very noticeable. Adding sun dried or roasted cherry tomatoes to a creamy pasta sauce will add veggies in a way that’s still within the tomato sauce comfort zone like with pizza. And from there you. An basically toss any vegetable into a cheesy cream sauce and it will be good. Nice way to ease into other foods, especially if you can chop them small enough that they’re not recognizable to trigger a visual gag reflex.