Definitely this, and maybe a motorized scooter for days that really require you to move around. Also check the conference site or call them to see if they offer any accommodations. But, OP, you’re probably not gonna be making it 15-25 miles a day no matter what you do. Be honest with yourself and others about your limitations and don’t push yourself too hard. Have a backup plan to get around if you need to.
For me it’s definitely Viscera Cleanup Detail. Super chill and satisfying cleaning game that I often boot up when I just want to shoot the shit with someone. There’s also quite a few custom maps after you get through the official ones.
Also Cities Skylines (the first one). Sometimes I just spend a couple hours watching my trains go around with a first person vehicle mod while I watch videos.