Something we did with our two yr old DGS. While sitting in the stroller, I would put some cold water onto the tray. He was happy to splash his hands into it. He got a little wet, but it kept him busy and cooler.
Also, a stroller with a deep shade or one of those super shades and you add on top. I always cringed when I saw little kids in stroller just baking away in the sun. One of those little fans would be good. We had a little one that was like a cage, so DGS couldn’t put his fingers thru and he loved it. (Just keep it away, while splashing in the water noted above )