There is a website where you can make a virtual one here:
https://www.gasfoodnolodging.com/visitedstates/
(Note that on that page they mention that there now is an iOS app as well.)
Granted its not as obvious as the map on the side of the camper, and wouldn't spark the conversation unless you printed it out and put it in a window or showed people your phone.
For myself I use push pins on a
Google Map.