For the RT1020 and the RT1050:
1. What actually configures the MPU during boot? Is it the ROM bootloader?
2. What memory regions are blocked/enabled during boot for each processor?
It looks to me like the RT1020 has the internal SRAM blocked, but the RT1050 does not.
I cannot see where this is documented.
Please can you expand on this.
First I would like to apologize for the late response. Regarding your question please see my comments below.
Yes, the ROM bootloader does this.
The internal SRAM is only blocked by the MPU during boot time on the RT1020.