It's straightforward to add m3u playlists of locally-stored files to the Apple Music app from the command-line. Is there any way to create and add a playlist of streaming content to the library, for example, based on the public URLs of the tracks?
If you export a streaming playlist from music.app as m3u/m3u8, it generates an empty file.
If you export a streaming playlist as xml, you do get the full content and metadata of the playlist, although the items appear to correspond to unique identifiers referencing the library, rather than the public URLs of the tracks (e.g. something like https://music.apple.com/us/album/night-arr-for-cello-piano-by-tom-poster/1720372829 or the same as an itms:// URI). It is possible to manipulate items in the exported xml playlist and reimport into the library, but that only allows you to access content that is already in the library, not add new content from Apple Music streaming.
So, in short, is there any way (command-line or programmatically, short of having a paid developer account and a MusicKit API key) to create and add a playlist that music.app will understand based on the public URIs for Apple Music tracks?