You can bring granola bars, fruits, cheese sticks and keep them in the stroller (checkpregnancy.com)
Also from Skip * Hop, the Treetop Friends Stroller Toys attach to the stroller bar or car seat handle (while in transit, not in car as apparently that's dangerous) to keep baby busy and interested while you're on the go. (havebabywilltravel.com)
Freddie the Firefly clips onto car seats or stroller bars, making it less likely that the toy will end up out of reach on the floor or ground. (thespruce.com)