I don’t think this is possible within the Wyze app, but I see that I can right-click an event video when using the Web Portal in Firefox (unsupported) and select Speed ➜ 0.5× from the pop-up menu. I don’t know if that would be helpful to you or not.
I can see that you’ve already voted for Enhancements for cloud events playback (e.g., slow motion, frame-by-frame, etc.) in the Wishlist, and you might also be interested in supporting this one:
For your current situation, your best bet for getting images may be pulling the microSD card to view videos on a PC, and I say that knowing that a given Cam’s location may or may not make microSD card retrieval practical. I’ve also seen suggestions that using the app’s Take Photo control during microSD playback can result in clear still images, like when trying to capture license plate information.