I don't play video games personally, so I'm not sure exactly what all equipment the kids end up bringing, but most libraries offer free video game rentals nowadays even for the Switch. The kids usually pack that up in their carry-on and hubs brings some kind of Roku thing so that we can watch Netflix in the evenings vs renting a movie from the hotel. He will also sometimes pack an HDMI cable with his laptop so that we can stream those onto the TV.
This part isn't technically a budget item, but if you're traveling around the States and have a library or museum membership be sure to check to see if they have any sister properties that you can use your membership at. Many libraries have free zoo and museum passes. IIRC national parks are the same way. Same with Children's museums and Science museums where your membership in one state will work there for free.