The solution using the Git commands to apply the changes worked, at least to some extent.
I’m not completely sure whether the output is truly running in 4:4:4, but during playback my Samsung TV switches every time to the calibrated Film profile. On the home screen, however, the TV switches back to the Graphics (PC) color profile instead of Film.
For me, this solves the problem well enough.
I also understand now that compiling the kernel requires a lot of resources. Thank you very much for your hard work.