I don’t work for Wyze, so I can’t tell you their official reason, but I have spoken to some other app developers about this and it sounds like there are a few issues that cause fewer developers to be willing to use Amazon’s App Store and why it remains so small and never really grows:
- It takes additional effort due to slightly different requirements
- Amazon’s developer tools and resources are not comprehensive or well-supported
- there are differences in guidelines and enforcement
- Fee and Royalty structure is different (I don’t know the details of this though)
- Small market share with a smaller ecosystem makes all of the above not worth it.
Amazon App Store did grow a little bit starting a couple of years ago when Microsoft announced supporting it on Windows 11 and making it the exclusively supported Android-based app store for Windows. Several other companies suddenly started to add apps to it, but then Microsoft announced they were canceling the project, and it seems to have died off again. 
For now, most people, including myself, just go grab whatever app we want on our Fire tablets from APKmirror and sideload it. Problem [mostly] solved…though it doesn’t automatically do updates.
Anyway, Wyze has indicated they are unlikely to add their app to Amazon officially. The wishlist is in a status of “Maybe later” but you’re welcome to vote for this topic here: