Okay, let me do some searching and digging and Ill see what else I have saved that might help!

Have you looked into FreeRTOs? I had to dabble the tiniest bit when working on a school project a while ago. Then I got into directly working with Atmel hardware bare metal. From 2018-2023 I spent learning early 8065 (pre x86 but tightly coupled to early stuff)

Something also worth looking into is the Cosmo LibC project https://github.com/jart/cosmopolitan. Justine is awesome and so is her discord! I mention this because most of her library is highly hardware optimized and plenty of asm to go around. 

There are a couple other folks in the discord like ahgamut and paulclinger along with some other peeps from NIST and other orgs that are just awesome to read and chat with too