The store models don't have it working for some reason. At least that's the story I got from a store rep. And it seems to match. That same store with my phone and SIM has 5G signals. The demo model does not. Perhaps something special about the SIM they used for the demos. Same thing with the S20s and N10-5G they have on display.
The 5G signal is on 700Mhz right now, and coverage into buildings and such seems better overall in my area. It's not really faster for me, but does get better coverage. Once they are able to start using the Sprint bandwidth, it should improve speeds.
I help install 5G around the country, and they're sending us out a TON now because they're pushing to get 5G installed on the smaller towers right now, so it wouldn't surprise me if we see expansion happening sooner rather than later