I think you should devise your own diet-making process. Then ask the questions which would inform your own process or do your own research.
As you say, your head could easily start spinning with all the information available if you don’t start by deciding what kind of information would be useful or useless.
Lists of high/med purine foods is only one of the ways to go about it. Such lists do not encompass all that matters about it but if that’s the way you want to go right now, fine. You need to start somewhere.
But in order to make it a good start, you need to use accurate lists. And in order to have accurate lists, you need to decide on what basis foods are supposed to end up on one list or another… if you watch carefully the amounts you’re eating, you might want to have lists based on weight or volume. If one the other hand you like eating your fill, you would probably find lists based on the caloric content of foods more useful.
Do I sound like I’m splitting hairs? Let’s look at a “green leafy veg”, spinach: one spoonful of spinach is certainly not high in purines. Spinach has got quite a lot of purines compared to most vegs but it’s still a fairly small amount. There are way more purines in meat. The thing is, how much are you going to eat? If you wanted to live on spinach, you’d have to eat a whole lot of the stuff (you might be surprised how much some people eat) while you could live on a much smaller amount of meat. So if you’re looking at how many purines there are compared to the amount of proteins or energy in a food, yeah: spinach is pretty high in purines.
And in order to end up with accurate lists, you’d also need to put an actual number on “pretty high”.
If that sounds too complicated to you, maybe forget about lists and try something else?
Limiting your meat intake to once a week is simple and does reduce uric acid for instance. But what are you going to eat instead?
The low-purine answer is simple: eggs, milk and so forth. But maybe you don’t want to eat or shouldn’t be eating dairy?
The good stuff in oily fish, you could possibly get through complements. Or maybe ditch meat altogether and eat oily fish once a week instead?
If you’re not eating a whole lot of vegetables anyway, you can ignore their purine content.
But if you’re going to eat lots and lots of vegs on a regular basis (which would generally be recommended), maybe lookup the ones you’re planning to eat in large amounts several times a week? Any amount of cabbage is fine for instance. Lots of vegs are totally fine.
Pills are so much easier!
And in case you didn’t know, allopurinol effectively neurtalizes purines so you can eat your fill of broccoli as long as you’re on that pill.