I'm looking for an app to play certain media files but that doesn't start playing immediately when a Bluetooth speaker is connected. The reason is that I teach English and carry the audio files for the course on my phone; playing them on my default music player will interrupt my playlist (banal, yes, but I don't want that) and using apps like VLC has the disadvantage of automatic Bluetooth playback on connection, which is mildly annoying because sometimes I forget to close the "secondary" media player (VLC, etc) and when I get in my car, both my playlist and "Lesson 4, activity 5" start playing.
I am aware there are some apps that select the default player on Bluetooth connection, but they don't seem to work with my phone, or clash with other apps I have (for example, an app that sets volume levels on Bluetooth devices pairing).
Is there any app that doesn't have any access to Bluetooth media and just plays media files? I've been using the default Video player in my Samsung Galaxy S8+, but there's no shortcut icon for it anywhere and I cannot add complete directories to its playlist (useful for long lessons).
I am looking for a media player in general, not necessarily "audio only", even if it costs money or includes ads, for Android devices. If the app costs money, I'd like it to cost at most USD $5; more than that is quite expensive for me.