Current status of ALFA Tube2HP support

The company I work for sells OpenWRT-based mesh WiFi units as an accessory for the data acquisition devices we build. Originally we used Ubiquiti Bullets, but a few years back we switched to ALFA Networks Tube2HP hardware because Ubiquti no longer allowed 3rd-party firmware to be installed. Our customized firmware is currently based on OpenWRT 18.06.1, but I've been asked to try updating to the most recent version to see if it might help with an issue that's recently shown up. I was rather surprised to find that no version of the Tube is selectable in 21.02.1; the hardware support table shows 19.07.8 as the last supported version. I'm not really sure how to interpret this - has support been permanently dropped? If so, WHY??? This is a perfectly suitable piece of hardware, well above the minimum specs, still in active production, that actually advertises itself as "OpenWRT Friendly"...

If the problem is just that nobody has gotten around to updating OpenWRT for this hardware, what can we do to help speed up the process?

The mach file based ar71xx platform has been replaced by the device tree based (and mainline supported) ath79 platform, but porting devices from ar71xx to ath79 is not an automated process and has to be done individually for each device. This can only be done by someone with physical device access and follows largely the same procedure as adding a completely new device (opened device, serial console attached, original development on the source level), so you'd be the perfect candidate to work on this and to provide a patch once you got it working (so it can be re-added in time for the next major OpenWrt release).

@slh, that's a bit outside of my comfort zone. The customizations I've done to OpenWRT have mostly been along the lines of config files and little Lua scripts; the only time I've actually touched the kernel was adding a custom LED trigger. I would be willing to give this a try, but after a couple of hours reading through threads about ath79 porting, I still have no idea where I'd even begin.