I looked at the app, here is a link:
https://withmascot.com/
It’s so much more than a card show app to know what dealers have. It appears to be a fully integrated inventory/collection organization tool that pushes product out to a dozen marketplaces. It’s a very impressive site and it seems like it could be a very useful for dealers, especially those selling online. My gut is they will expand it to work for other products - easy extensions would be coins, comics, and other slabbed items. This is likely the future…
For now, I will hold dear to my spreadsheets and Flickr account. I expect many other pre WWI collectors will do the same. But I bet I will eventually give in to the inevitable and utilize a tool like this- just not today!