You keep saying Apple claims this or that, and I think you're listening to reviewers or other sources and conflating their statements to Apple claims.
For instance, Apple never claimed there were new speakers - just that the T2 chip is used with variable EQ to produce better base.
Didja just buy your iMac Pro or something? You sound very defensive about that machine.
The fact of the matter is that I think it would be foolish to buy a new iMac Pro at this juncture - you can pretty much get just as much machine for a lot less money - and the Pro is Intel server chip based. Yes, the thermals on the 2020 iMac aren't quite as nice, but you can get user upgradable RAM a ton cheaper. Heck, you can get just about everything a ton cheaper, and the consumer based Intel chips have QuickSync.
When they finally get around to adding it to FCPX, you will have the ability to use the Navi 5700 XT's encoders which will widen the gap.
The problem with the iMac Pro is that it's an aging machine with a lot of old hardware in it.
As to Apple's marketing: I haven't heard squat out of Apple about this machine other than what's on the product page - I think you should go back to the product page and reread it. Any advertisements I've seen pretty much just reiterate what's on that page.
I come from a 2017 iMac 5K and there's a ton of improvement from that top-of-the-line model. There was a steep difference between the 2017 iMac 5K and the iMac Pro, but a lot of that difference has evaporated when compared against the 2020 iMac 5K.
Should you upgrade from the iMac Pro to the 2020 iMac? Probably not.
But the almost 5K price on the 2020 machine you're quoting is a 5K speced up - now spec up the iMac Pro to get similar capabilities and capacities and price that out - don't just compare a speced up 2020 iMac 5K against a base model iMac Pro.