What are some good whole-body strengthening exercises?

There are dozens! Burrpees are perhaps the best overall best single exercise you can do especially if you pair them with a push up and a jump at the end of each one. Squats, planks, pushups, mountain climbers, superman pose, dips, oh! there are dozens of great exercises! Check out this website to get started: https://www.acsm.org/docs/brochures/resistance-training.pdf.