Hello Lorenzo,
Thanks for your interest in flashrom! Unfortunately, we are not participating in GSoC 2023. Also looking at the program timeline for 2023, the deadline for contributor application is already over. For this year, it's too late for you to join the GSoC program for any organisation.
However, maybe you are thinking of potentially joining next year: that's cool. You can also contribute to flashrom at any time independently of GSoC or any other program, but just to be clear: that would be your personal contribution, and not paid.
In any case you need to have a look at guidelines and see how it goes: https://www.flashrom.org/Development_Guidelines https://www.flashrom.org/GSoC https://www.flashrom.org/Easy_projects
Good luck!