RIP
Hi Nenad and welcome from me too.
Depending on what you want to do, you have many more options. As @CyberGene is saying, if you do not need velocity nor aftertouch (or at least if you don't need the subtle precision of piano) you can more easily use the GPIO pins on a Raspberry Pi Pico, of which there are many more than ADC channels. That will allow to do your project with very little soldering, and perhaps no custom PCB. See https://github.com/davidedelvento/Mybrid for details.
If instead you do want high quality velocity (and perhaps precision polyphonic aftertouch), see https://github.com/jkominek/piano-conversion



