QMK runs on any USB-capable AVR or ARM microcontroller with enough flash space - generally 32kB or more, though it will *just* squeeze into 16kB with most features disabled.
There is limited support for one of Atmel's ATSAM microcontrollers, that being the [ATSAMD51J18A](https://www.microchip.com/wwwproducts/en/ATSAMD51J18A) used by the [Massdrop keyboards](https://github.com/qmk/qmk_firmware/tree/master/keyboards/massdrop).