[lzlz]

Actually using C or C++ is the most straightforward painless way to learn kernel dev. C is not complex at all. What you need to learn first is something like what nand2tetris offers, at least the first part. Usually you will have to do some variation of nand2tetris in the first or second year of undergrad.

[glouwbug]

Correct. Try these two:

https://github.com/DoctorWkt/acwj

https://github.com/cfenollosa/os-tutorial