I share your frustration when I want something, and I do a ton of research, because it doesnt exist, and the use case makes perfect sense to me, but no one else seems to want it or at least no manufacturers want to make it.
As already mentioned, serious tool users won't want what you're describing because of the fact different sized screwdrivers are used on different sized fasteners. A Phillips 00 which is for eyeglasses, very small, will require much less torque than a Phillips #3 which is a huge size screw. So manufactures make the make the handles different sizes because for actual using them, having different sized handles makes it better to use the tool.
It sounds like you want to optimize for aesthetics in storage versus optimizing for use. You might be able to find some cheap crappy Chinese screwdriver sets that all look the same. They will be terrible screwdrivers, but you're optimizing for looks, not function, maybe that's a way to go.
One option to consider might be 1/4" bits. Maybe an X-in-1 Screwdriver with reversible long shank bits.
For example these Tekton 6 in 1, and they sell individual bits so you can get all of the different bits, which are all the same length and come up with some visually nice storage solution for that:
Shop pre-assembled multi-bit drivers, including Phillips, Slotted/Flat-Head, Torx®, and Nut Driver tip options, with interchangeable bits. Handles are molded in the USA.
www.tekton.com
If you want something super high quality and custom, you might be able to get snap on screwdriver shanks that be customized into the same size handles.
The problem is that each diameter shank of tool, like Philips 3 will be much larger diameter than P00 because P00 head is so small, and they mill the shaft to match the head. Which means the hole at the end of the shank will need a different sized hole in a screwdriver handle.
Personally I think you should come up with a different organization solution if the physical appearance bothers you, maybe one where the shanks are hidden, like a in a "sheath" and the front is hiding all of the shanks. Like a rectangular shaped storage box, with holes on top and the screwdrivers all sit in there, pointed down. and you can't see the shanks at all. Different sized handles sticking up may bother you though.
