I'm not so sure about that anymore

Tell your A"I" to generate you an SMP-capable scheduler, aware that each core cluster can be of a different perf and power consumption class. Not a vague explanation of one. Real code, please. Let me know how that goes for you. That is one of 1e9 problems that need to be solved to make a modern OS, not even one of the harder ones.

You don't have to replicate all the insanity that goes on in a modern OS.

Lock threads to a particular core on creation, every core does a Round-robin over all threads. You're 50% there.

Have the core detect congestion, and move yeet threads to another random core when it's congested. You're 75% there.

Use three lists for priorities instead of one. You're 90% there.

Make up for the other 10% with sane design in other subsystems.