The WVM file extension relates to WAVE software. WAVE is a gas dynamics simulation tool. The wvm files store input data for WAVE. You can import wvm files into the WAVE application. There is no way to convert wvm files to other formats.
WVM files are video files. Google Play Movies & TV app uses them. The app plays purchased or rented movies and shows. WVM files store videos downloaded from Google Play. The format resembles MPEG-4. WVM files also encrypt via Widevine DRM. This protects copyrighted video content.
Opening a WVM file requires a media player. The player must support wavelet compression. Wavelet compression shrinks file size. It splits an image into waveforms. These become small, compressed files. Video quality stays high despite smaller overall size.