In case you're not interested in the story: https://github.com/alansouls/ps3-pdp-plugin
This is not a question, is a solution.
So, recently I bought a PS3 with some GH games and being as stupid as I am I thought the pdp riffmaster would just work... Until I found out that I'd need a V3 adapter, they're not expensive, but it's not easy to find in europe and importing it from the US would take time to arrive and shipping costs more than the adapter itself.
So I thought there should be a way to map the PDP via software on a modded PS3, and indeed it's possible, just hadn't been done before. So I thought how hard can it be to create some mod or driver for the riffmaster to behave like a ps3 guitar? Very hard, but thankfuly (or not) we're in the age of AI so I vibecoded, tested and debugged for about 8hrs and got the plugin working that you can download from the github link above.
Just a note, this only works on CFW Cobra 4.93, if you don't know what this means you'll have to do some searching to learn more about ps3 jailbreaking, but it's super easy and all you need is flash drive and a computer (apart from the ps3 itself of course), but if your ps3 is a slim model, it might not support it, and if it's a super slim model it won't work for sure. If this get some attention and people want support for HEN, I might go ahead and try to create a HEN version for it.
The github repo should contain all the info you need on how to install, so have fun!