I'm retired from tech and a high school teacher these days and allowed to teach wack/out of level things.
I would love to teach operating systems with NetBSD, but between the space hardware stuff I do and the Verilog/digital logic/microprocessor architecture class I teach, I soak up all the interested students' elective slots.
Here something you might like : CS631 -- Advanced Programming in the UNIX Environment - NetBSD https://stevens.netmeister.org/631/netbsd.html