Pullout pantry inserts aren’t Economical to buy or to install. A couple of thousand in that project. You need a cabinet maker or installer. Not a handyman. https://www.cshardware.com/14-soft-close-wire-tall-pantry-accessory.html

Have you tried the container store? They have tons of pre fab closet options. Maybe something would fit your cabinet.

Try Lee Valley Hardware. Lots of options.

https://www.leevalley.com/en-us

This is a kitchen component that needs to be well thought out, and worth the expenditure. Pullout drawers above waist level are unusable. I would leave 2 shelves at top with a lot of clearance for items like tall cereal boxes, which seems to be the trend, or other easy to grab items that are not heavy. A deep pantry closet is an easy place to lose items that get shoved to the back.
3 drawers of varying depths so items don’t have to be stacked on top of one another and can easily be identified. Canned goods, herbs and spices can lay on their sides in shallower drawers. Flours, sugars can be placed in deeper drawers.
Get some cardboard moving boxes to approximate your needs. I don’t mean put thos boxes in the space but get a visualization of what works.

Look at Rev-A-Shelf online....they make pullouts that could be attached to your existing shelves I bet. Then you could DIY.

Agreed....First I would see if a local cabinetmaker has someone to retrofit the pantry with a full pull-out unit (remove the shelves and build a whole rollout unit to fit within) or keep the shelves and add individual pullout trays on glides attached to the shelves. The tray-on-glide idea would slightly reduce the vertical height of each slot. And yes, go to The Container Store if there is one within a reasonable distance for a possible solution, exact measurements in hand. There may even be a ready-to-assemble stainless steel rolling shelf unit at TCS.

Probably your cheapest option is gliding mesh baskets from the container store (elfa line)

You need side gliders screwed into the wall that are thick enough so the basket or drawer clears the trim.

If you go the container store route and completely re-do the whole thing, someone there (for the price) will probably help you figure out how many shelves, pullouts are needed, etc. However, any other route (if you purchase and handy person installs) you will have to figure out how many pullouts (as someone else noted, too high and you'll never be able to reach it). A long way to say -- You're probably going to have to figure out what you want to store in there, and how it might work if you were to have slide out baskets or shelves installed. And, that said -- if you're happy to work with your shelves as they are, this is not a hard project, as the slide out baskets will probably only require installing with screws into the shelf. Yes it will be a challenge for all but a slim person to get to the back of the cabinet to screw in the back screws, but that's probably all that is required. I put pull out baskets under our bathroom sink cabinet (with more room to maneuver...cabinet was 2x as wide as the basket) and that was the challenge, to wrangle back there to screw in the tracks. If your shelves are removable that will make it 100% easier to install tracks. Good luck!