>>28486375 (OP)>Is there an open-source or open-source flash-able Head unit?Yeah, they're all over AliExpress, anywhere from under $100 to no more than $200-300 at most for one with the most ram and newer processor.
I wouldn't be able to tell you which brand head unit can run which version of Android especially since there are so many, but in just a minute of searching I was able to find someone with an ATOTO head unit (available on Amazon/Ali) that managed to get into the bootloader and root it, even installing Kali Linux of all things kek.
I'd go down that rabbit hole if that's what you're after, stay away from those expensive name brand HUs since they're usually far more locked down (and they're all made in China nowadays anyway, you're not getting a Japanese Nakamichi or German Blaupunkt anymore)