I know it's probably an intentional exaggeration... but are there really any microcontrollers over 1 GHz core clock? Fast I know of is ST at around 600 MHz.
[1] https://www.mouser.com/c/semiconductors/integrated-circuits-...
Cortex-M is a microcontroller, without MMU (can't run Linux etc.), and typically has internal RAM and flash.
Only the NXP i.MXRT1170 reaches 1 GHz CPU clock, and this is not multi-GHz as the prior comment declared.