The Amazon listing is still there but unavailable. But there are some things I notice with the Vello grip that make me wonder why they even bothered to bring it to market in the first place.
Vello BG-N18
The biggest thing I notice is this grip requires you to remove the battery and battery cover. Not that weird, as the original D80 battery grip worked like that. But the Vello only has a single battery slot in it. So you add the extra bulk and do not gain anything for extra battery power. The D80 grip at least had 2 battery slots and you could change them individually as you worked. This is just stupid.
Controls: There basically is none. Shutter release button and nothing else. Useless. No control dials or function buttons.
The D7500 just was not built to take a vertical grip by Nikon. That is why nobody has really made one, and when it was done aftermarket it was a useless item.
But that is just a rant from somebody who has owned the D80 and D7000 battery grips in the past. I have given up on grips since I have adopted L-Brackets as standard equipment on my camera bodies. In a pinch I can use a USB power bank in my pocket and a long USB-C cable to bring extended power to my Z5 with no added weight. But yes I do have to hold the camera funny in portrait orientation. For the 8% of photos I take in that orientation.