Honestly, I've seen a lot less of this than I'd have expected. Lots of discussion, plenty of experiments or toy implementations at the level of individual teams (often driven by one or two enthusiastic individuals), a few proofs of concept for internal services at a more strategic level, but pretty much nothing beyond that.
This is in the UK where there's currently a big focus on data sovereignty in general, and I'm genuinely surprised by how little that's spilled over into demand for inference sovereignty (so far).
I still expect demand to grow substantially, but I've been saying that for the past couple of years and am beginning to wonder if there'll need to be some sort of trigger event before it happens (eg. the datacentre bubble bursting, or some sort of major scandal).
Non-tech enterprise was already doing this years ago.
Regulatory reasons, privacy reasons, security, etc. They want on-prem and total ownership of the data. Sometimes air-gapped.