Thanks all for the answers!
I will note that the Ultibo.org multikernel has 32 bit support for all ARM models.
Pascal code, but the constants are .. constant.
E.g.:
https://github.com/ultibohub/Core/blob/master/source/rtl/ultibo/core/bcm2837... ../platformaarch64.pas ../platformarmv{6,7,8}.pas
All of this is running in a single address space in supervisor mode, but rotating cube playing video on RPi3 is evidence of hw knowledge.
One needs to steal ideas from the best. ;^)
Thanks again, -KenD