I missed the PL011 discussion. :(
I had looked at the issue and found about 18 different versions.

I tried to create a taxonomy:
- read/write_volatile (with constants)
- read/write_volatile (with constants) + bitflags
- read/write_volatile + repr(C) + bitflags 
- svd2rust
- tock_registers::register_bitfields + tock_registers::register_structs
- A few with different MMIO wrappers (struct or macros)

They also have also some distinct differences in feature set:
- Proper initialization function (the ones lacking it will not work on real hardware, only emulators or VMs)
- embedded-hal-nb / embedded-io traits support
- Support for interrupt handling

So yes, the PL011 is a pretty simple peripheral and the most interesting to start with (if just to get some debug output).
Can we learn from the diversity of those implementations, and come away with some best practices?