i was able to use betepok's suggestion with a slight modification on the april 10th (5.0.7) nightly.
cp /lib/firmware/rkwifi/fw_bcm43456c5_ag.bin /lib/firmware/brcm/brcmfmac43456-sdio.bin
cp /lib/firmware/rkwifi/nvram_ap6256.txt /lib/firmware/brcm/brcmfmac43456-sdio.xunlong,orangepi-3.txt
the second command is a bit more complex; got the magic filename from dmesg errors. hope this helps.