I have had a call with the Vexpo organizer.
Long story short; we probably won't get a sponsorship, but that is mostly because the vast majority of their slots are already booked and there is apparently a large amount of competition for the remainder. TVA is a vague enough 'product' that working with it would be somewhat unconventional, but no objections were made otherwise. I will not reveal further details of what we discussed because I was specifically asked to keep it private, as I should have been.
Even so, I did not get a hard refusal just yet, though I'm proceeding with that expectation in mind.
That said, the rest of the conversation gave me a great deal of hope that this will be a far, far better experience than Offkai. The staff are hiring professionals for their technical needs and say they have had far more volunteers than they ever expected.
The 1,500 pound sponsorship would've included a dedicated booth, which I would have absolutely snatched up if it was still available (it was already fully sold out). The idea of having a TVA-themed booth alongside vtuber booths is so hilarious that I'd have paid for it out of pocket. Maybe next year.
To put in perspective how nice this call was (or, if you want to be massively, massively cynical; how well PR-rizzed I was) I'm now contemplating getting one of their Akasupa tier passes instead of just a regular one.