Would OpenWRT Create a Hardware Firewall Firmware OS like PfSense that we could Flash to a BT HomeHub 5 Type A, saves wasting a Server to do this task.
Could call it:
WatchGuard-OpenWRT - Hint.
or BT Hardware Watchguard, Encrypted DNS, OpenVPN as default blar blar etc.
OpenWrt is a firewall os. No additional server needed. That is more than enough for the majority of use cases.
If you want to bring up support for your device then you will need to complete that work yourself. Device ports require the dev to have the device on their desk and have the interest in the architecture to want to do it.