Update 15/11 2022: I’m pretty sure the app is DEAD.
Someone made a Handy script player for iOS and Android:
https://www.reddit.com/r/theHandy/comments/libwz6/sync_player_ios_and_android_video_player_for_your/
Appstore:
iOS: https://apps.apple.com/de/app/sync-player/id1552607939
Android: https://play.google.com/store/apps/details?id=com.tnx.sync_player
Demo: https://www.youtube.com/watch?v=0i-O4byQjsc&feature=youtu.be