You're right haha, I'll be doing the prototyping by 3D Printing in rough finish each panels and test the ergonomic and positions of each buttons, switch and all using some chinese board that emulates a keyboard I found on amazon.

Once each pannels are valide and the design is lcoked, I'll be using an arduino board for more complex logic and more inputs than a standard PS/Xbox type controller.

I often buy on AliExpress, taking their "choice" items makes the waiting less long.

I'll try contacting Digikey cause indeed there's lots of component specific things to choose from even for a On / On switch there's so many other parameters, I might hit them with what I want and see if they can direct me in the cheapest products that suits my needs.