Old news.
https://www.cnx-software.com/2019/02/21/stmicro-stm32mp1-cortex-a7-m4-mpu/
This happened in 2019. STM32MP2 release is coming soon, so we're well on our way to having the 2nd generation of STM32-microprocessors.
I'm mostly a MCU fan. MPUs are awesome too, though the gross complexity increase makes my head spin. Supporting "proper" DDR2 and 512MBs sounds awesome though, my personal VPS for years has always been just a 512MB instance because that's enough for personal websites and simple Linux tasks.
512MB DDR2 on a single-core ARM A7 is exciting to me. But... in a way that feels forbidden, too complex for me to truly get into and try to use. I'd probably just buy things like Beaglebone Black ($50 at the moment), or Rasp. Pi (if it ever comes back to a good price).