I don't know how you get paid for it, but if you want to write your own kernel, I'd start with an osdev tutorial. started with this one [1], but this one [2] has a promissing name... and I haven't really looked around.

It helps to have a concept to guide you too, but you can certainly make some progress on the basics before you figure out what you really want to do.

[1] https://wiki.osdev.org/User:Zesterer/Bare_Bones

[2] https://osdev.wiki/wiki/Multiboot1_Bare_Bones

Thanks. I got all the resources covered. But I don’t have the energy to work on them as a side project any more. Alas! I wasted my younger days and hope you fare better!