I have multiple video series in different folders.
Need a video player with tracking feature - remember which video last played.
Almost got it : the great VLC has it. https://www.vlchelp.com/grouping-listing-video-orientation-android/
Still, I am looking for other apps…
Try Nova https://f-droid.org/en/packages/org.courville.nova/ It scan your videos for movies and series and then it downloads the poster, background art, information of the serie/movie and information of each episode, you can also download subtitles.
There’s also kodi https://f-droid.org/en/packages/org.xbmc.kodi which I think is a more complete option, but it was designed for TVs and not for phones. I also think the fdroid version is generally outdated.