There are very few developers or other contributors for Broadcom based devices, as there are no drivers for:
- xDSL modem
- cable modem
- phone features (FXS, DECT, ...)
- hardware offloading (packet engines)
- WLAN
...and Broadcom being openly hostile towards opensource.
With the prospects of there never going to be drivers for the primary features (wifi), it makes little sense to waste time on that steaming pile of proprietary garbage - and few even try (why would you, if Mediatek and QCA offer equivalent hardware that can be fully supported, vote with your wallet).