Is it practical to make home-made membrane switches in low quantities?
There's a 'metal snap dome' style button that you can use which simply sits loose on the keypad. It can be held in place with adhesive, in a membrane, or with some kind of a housing. This overlays your PCB with the contact pattern.

They give a nice tactile feel without consuming a lot of height. And because their placement is defined by the PCB, button arrangement is easy to customize.

Keystone (and a billion other places in China) make them. Here they are on Digi-key for reference: https://www.digikey.com/en/product-highlight/k/keystone/metal-key-pad-dome-switches.

Here's more description of their application: https://www.sager.com/manufacturers/keystone-electronics/metal-key-pad-dome-switches-from-keystone/