USB haas operator panel interface

Apoligies for the long post - but I have been looking at panels for my upcoming LCNC retrofit and lo and behold, a cheap used Haas keypad came up. So, was wondering if there's still life in this project? Has anyone managed to map the whole (or most) of the keypad by now?

And here comes the wordy part:
Actually, I had to ask the AI overlords to explain why making the keypad work on LCNC is such a challenge. And it seems mapping it is the easy part and can possibly be done with some sniffer code. Once mapped, passing on button presses as USB HID is doable, too - and more so with the right MCU. But then there's a bit of an issue in that HID is pretty strict and wont pass on CNC-specific "characters". But a gamepad library would (as generic button numbers) and you could run two of them (HID + gamepad) on the same, newer MCU over just one USB connection. (Oh, turns out the two-protocol approach is AI's idea. Here, in the forum, it was proposed to use funky combo presses for the CNC buttons).

So far, so good? (If AI is correct on all of this). But then the real issue is, it's actually safer and much preferred to run this with Smart Serial and bypass the LCNC host computer and instead talk to the Mesa cards directly? But that protocol is not open, right?

Personally, I think I am OK with the USB method or a sort of hybrid - I could split a handful of more important controls out and run them direct to Mesa DIs and keep the rest over USB. Wouldn't that be OK? And if so, is it correct that the USB method is pretty doable, but perhaps the project stranded on Smart Serial access?

OK, so the reason I am trying to wrap my head around all this is that I also see a lot of other used panels apart from the Haas (I tap into the used market in Asia). Some of them may be locked down as I see some more fancy chips on the PCBs but some are just a "dumb" matrix. And for some of the locked own ones, they could possibly be rewired as a matrix. And some of them are so cheap and pretty neat, I might give this a go - but it would be nice to hear if what (A)I wrote above holds true. If it does, I think am up for it. 

I went a bit deeper into this rabbit hole and picked up some used panels. Still waiting for them to arrive. Not Haas though - I missed out on that deal.

But it turns out, sometimes (often?) these panels are a mix of both a raw matrix output and USB or PS/2. Like the Syntec and their clones as shown here . In the latter case, the "CNC'ish" buttons are all just a matrix but the keypad/numpad come out as a standard PS/2 protocol.