This might be sacrilegious to suggest and I haven’t read the thread in detail but could you not just use pre-ground coffee in a Technivorm?
I’d be interested to see if there’s a marked difference in flavour quality in B2C coffee vs pre-ground in a decent filter machine?
We had a B2C machine on each floor at the last agency I worked at (not sure on model, was massive and had a touchscreen) and it was pretty terrible. I never dared to use the milk functions as the thought of the old milk in the plumbing put me off. I’d have taken pre-ground filter every time. And in fact I did, with a V60 at my desk.
Edit: I see you need to be able to make milk-drinks on demand also. I guess B2C is the only way!