Indeed, the memory model has a decent impact. Unfortunately it's difficult to isolate in measurement. Only Apple has support for weak memory order and TSO in the same hardware.

Oh there’s an interesting idea. Given that Linux runs on the M1 and M2 Macs, would it be possible to do some kind of benchmark there where you could turn it on and off at will for your test program?

This has been done in fact: https://doi.org/10.1016/j.sysarc.2024.103102