Hi,
If you don't intend to make any curries, then I would aim to make a 2 onion base rather than kilos of onions and litres of gravy.
If you can't find a small base gravy via the forum search, then choose any popular recipe and scale it down to 2 onions.
Once cooled and blended youre ready to make a curry. A 2 onion base should make roughly 700ml. (Or 2 portions of base gravy/curries) or enough for 20 odd pizzas

Now you can choose any recipe on the forum to make a curry sauce for your pizza. Just leave out the solids, e.g. meat/chunky veg and reduce to a consistency of a tomato pizza base sauce.

p.s I've found that small bases tend to be quite sweet on their own anyway, but you can always add sugar or ketchup to your curry pizza sauce.