I would probably be careful with wrist conditioning while your wrist is sore and swollen, but here is a link to a blog post with video about 5 wrist conditioning push up exercises that I have found useful in strengthening my wrists for an adult gymnastics class.

http://www.samsrawtruth.com/2011/01/wrist-conditioning-pushup-series.html?m=1

This exercise series comes from Coach Sommer of Gymnastic Bodies. Here are a couple of links to his forum which also provide some good information on technique for these exercises, to make them harder, to make them easier, etc.

https://www.gymnasticbodies.com/forum/topic/54-wrists-endurance-including-wrist-pushups-pt1/
https://www.gymnasticbodies.com/forum/topic/543-question-about-wrist-pain-incl-wrist-pushups-pt-2/