Rasberry pi is not only closed source but intentionally has little documentation. Use it, don’t use it, idgaf. But stop calling it an open source project. That’s 100% a lie. If you want truly open source cheap Bitcoin hardware check out Krux. https://www.nobsbitcoin.com/krux-v24-07-0/
“Perhaps the biggest challenge to an open-sourced alternative to the current firmware is the fact that the hardware itself is also closed source and largely undocumented. This is of course not an ideal situation, but has become a widely-accepted tradeoff judging from how many have been sold.”
https://raspberrypi.stackexchange.com/questions/116356/whats-firmware-parts-are-needed-and-closedsource-for-rpi-4