I've definitely been noticing the 2-digit ARM Cortex Mxx series popping up.
Cortex M23, Cortex M33, and now M85. Its a decent way to see which cores are more recent, because the previous branding (M0, M4, M7) was about cost and not so much about speed.
I've heard of Helium, and I'm also a big fan of SIMD-compute in general (I moderate https://lemmy.world/c/gpu_programming). There's innate performance benefits if you can manage to get SIMD code out, but its still a bit of an arcane subject matter. Helium was supposed to be a way to describe SIMD for microcontrollers / lower-power stuff.