I found an Android app that's better suited for playing my looping mp4s. (Patreon)

Google Play：Flipiclo WebP, Webm, MP4 Player

Set it to loop a single video, with a quick click on the right to skip to the next one. You can figure out the details, but honestly, with this feature, I won't need to bother making animated WebPs just for the sake of easy switching anymore XD...

(The provided file format will not be adjusted at this time.)