Commands necessary to enable WLAN support on Raspberry Pi 400 for Venus OS v3.00, https://watenan.uk/2023/07/02/enabling-wifi-on-a-raspberry-pi-400-with-venus-os/

RaspberryPi400WlanSupportOnVenusOS.sh

mount -o remount,rw /

cd /lib/firmware/cypress
cp /run/media/sda1/cypress/cyfmac4356* .
chmod 644 cyfmac4356*

cd /lib/firmware/brcm
cp /run/media/sda1/brcm/brcmfmac4356-pcie.gpd-win-pocket.txt .
chmod 644 brcmfmac4356-pcie.gpd-win-pocket.txt

ln ../cypress/cyfmac4356-pcie.bin brcmfmac4356-pcie.bin
chmod 777 brcmfmac4356-pcie.bin

ln ../cypress/cyfmac4356-pcie.clm_blob brcmfmac4356-pcie.clm_blob
chmod 777 brcmfmac4356-pcie.clm_blob

ln ../cypress/cyfmac4356-sdio.bin brcmfmac4356-sdio.bin
chmod 777 brcmfmac4356-sdio.bin

ln ../cypress/cyfmac4356-sdio.clm_blob brcmfmac4356-sdio.clm_blob
chmod 777 brcmfmac4356-sdio.clm_blob

ln brcmfmac4356-sdio.AP6356S.txt brcmfmac4356-sdio.khadas,vim2.txt
chmod 777 brcmfmac4356-sdio.khadas,vim2.txt

ln brcmfmac4356-sdio.AP6356S.txt brcmfmac4356-sdio.vamrs,rock960.txt
chmod 777 brcmfmac4356-sdio.vamrs,rock960.txt

cp /run/media/sda1/brcm/brcmfmac43456-sdio.bin .
chmod 644 brcmfmac43456-sdio.bin

cp /run/media/sda1/brcm/brcmfmac43456-sdio.clm_blob .
chmod 644 brcmfmac43456-sdio.clm_blob

cp /run/media/sda1/brcm/brcmfmac43456-sdio.txt .
chmod 644 brcmfmac43456-sdio.txt

ln brcmfmac43456-sdio.bin brcmfmac43456-sdio.raspberrypi,400.bin
chmod 777 brcmfmac43456-sdio.raspberrypi,400.bin

ln brcmfmac43456-sdio.clm_blob brcmfmac43456-sdio.raspberrypi,400.clm_blob
chmod 777 brcmfmac43456-sdio.raspberrypi,400.clm_blob

ln brcmfmac43456-sdio.txt brcmfmac43456-sdio.raspberrypi,400.txt
chmod 777 brcmfmac43456-sdio.raspberrypi,400.txt

mount -o remount,ro /

see also this forum post: https://community.victronenergy.com/questions/204286/venus-v294-wifi-bluetooth-on-raspberry-pi-400.html?childToView=215957#answer-215957