Earlier quoted context omitted.
Most of them? Pretty much every ARM board supports an SRAM boot stage, for example. If you're using U-Boot, it's pretty likely that there's a SPL running out of SRAM somewhere in there.
ARM is a microcontroller architecture.
2) SRAM is almost always on the die, not external. Here's a die shot of a random STM32 (cortex M): [1]. The SRAM is quite obvious.