Playlist combination

Description

I would like to request a feature to allow the aggregation of multiple playlists in a single higher order playlist.

Why?

My reasoning for this is, that I have multiple media sources (Plex for High quality stuff that is correctly tagged and navidrome for any low quality stuff and singles).

I have a playlist in plex that I keep synced to the app. I would now like to create a second playlist in navidrome and have an option to combine those two automatically. Creating the playlist directly in the app instead would prevent me from syncing it to other devices.

Graphic Description

Implementation idea

I think the best way to go about this would be to add a filter for smart playlists to include all songs from another playlists automatically.