b43: Putting out feelers on adding support for BCM4360

[Helga K <Strike0347@proton.me>]

Hi,

I'm a C dev that works in network hardware testing and bringup.
I'm extremely tired of the myriad issues of the broadcom-wl driver, and I'd like to add 
support for the BCM4360 card to b43 instead. The last few times this card was mentioned
by developers were:

* Arend van Spriel in 2015 saying support would be unlikely because Broadcom didn't
  clear it and because it'd require adding VHT support to brcmsmac (that hasn't changed in 
  10 years - brcmsmac still doesn't support VHT+ hardware)
* b43 developers adding a stub saying its PHY wasn't supported (but could be in the future)

AFAIK support for this card in b43 is feasible - it's only AC PHY operations that are missing.

My questions are:

* Is it possible to merge new functionality into the driver given its orphaned state? I'm
  not capable of taking over maintaining b43.
* Is anyone in the community broadly familiar with reverse-engineering Broadcom hardware
  and can bring me up to speed with the state of the art?

Thanks in advance,
Helga