I can’t find an interface in Plexamp for editing playlists or adding songs to playlists. I know it’s in its infancy and not exactly a supported app, but I would love to have that feature.
Plexamp is (at the moment) solely about playback… no editing / management / …
Not yet, at least.
2021 clean-up: implemented (playlist creation, add, remove items – though no option to edit the playlist metadata or delete the playlist itself)