Bouncy house is such a great toy for kids for summer that will keep them occupied for a couple of hours. The bouncy house in this video is from Step4Fun that can be used indoors and outdoors. It has a ball pit pool, a slide, a basketball hoop, and a ball target. Size is perfect for a 3-year-old.

Here's a link to the product, if you're interested: https://amzn.to/3PofM8e (affiliate link).