Qmk supports the keyboard, and there are options for mapping mouse movements to keys if you’re willing to get your hands dirty in the firmware. I’ve used that feature in the past and could never get used to it, but it’s an option
You might want to consider the TEX Shinobi (or DIY version with hotswap sockets). I have one and it is very good. The main downsides are that it’s not low profile (Cherry MX instead of Kailh Choc), and the hardware and firmware aren’t open source. (I also used clicky Cherry ML-compatible switches for the mouse buttons, which are much better than the linear Cherry ML’s that came with the board, but were very difficult to source.)
I think the pointing stick used by the Shinobi might also available as a standalone module, probably not as purely free/open hardware, but as a simple sensor that probably has a data sheet available. The difficulty is that it requires modified G, H, B key caps (which the Shinobi has in its design).
Lastly, please don’t call it that. There’s no need for such an overly sexualised name - “trackpoint”, “pointing stick”, or “mouse nub” work just fine to describe it.
Sorry for using the controversial term. It’s the one I knew, but both “trackpoint” or “nub” sound accurate to me!
Thanks for pointing to the TEX Shinobi! It looks by far too big and clumsy for my taste, however.
Looking at https://imgur.com/a/0VHce, I wonder, if it were possible to insert a Lenovo nub in the MNT keyboard… Nice project for the time after retirement.
My Lenovo keyboard has the “B” only slightly modified. It’s probably fine to install the nub a little bit higher and modify only “G” and “H”. Less work and maybe even a better position.