Thanks for this. I finally got the chance to give it a go, although slightly limited as my raspbian-lite has no gui, and programming is working. One oddity regarding the pinetime-rust-mynewt release v2.0.5 - the flash scripts in scripts/nrf52-pi/ call openocd/bin/openocd but fail as that's an x86_64 executable not an arm one.
That seems a reasonable solution to the cross-platform complications, and well done for trying to make it work for everybody. I wasn't exactly following the instructions so it's fair to expect things not to go so smoothly.