If I had no problem with devoting the time and money, contributing to the kernel (especially in a topic as obscure as making the extra buttons work on a 20-year-old laptop) is at the top of my bucket list, and I am definitely going to be doing it in the near future when my calendar clears up a bit. Exquisite write-up and OP's simple writing has a motivating ring to it, and I'm now on the local used marketplace lookin…
If you want to find devices that still need hardware support under Linux, I highly recommend trying to get a mobile Linux distribution to work on an old smartphone or tablet. postmarketOS in particular has a really good devices page [1] showing missing feature support at a glance, as well as guides for porting to new devices [2] and porting features from an outdated vendor-provided Linux fork to the upstream kernel […
And the pmos wiki is severely lacking IMHO.