This is 'The Child Passenger Window Decal' created by FanWraps and available for pre-order from Entertainment Earth (among other places, shipping January 2020). The see-through decal makes it appear Baby Yoda is chilling in his little hover pod and peering out of one of your passenger windows. Or, if you're like me and attached the decal to your windshield, like he's driving. What? He's fifty, it's cool.
Thanks to Dunc, who agrees there are going to be hundreds of these things in Disneyland's and Disney World's parking lots on any given day.