So, the ways I’ve mostly seen this done before:
- One YouTube video: standalone recording
- A YouTube playlist, specifically styled to be release-like (including title, a cover, etc): release
- A streaming-only release on Bandcamp: release
- A SoundCloud set: release, at least unless it’s very un-release-like (“some mixes” with no attempt to make them a unified thing).
- A SoundCloud track: standalone recording, unless there seems to be some intent to make it single-ish (actual designed cover, assigned catalog number, something like that)
- A streaming-only Spotify/Tidal/Whatever release: release
I’m not saying this is how it necessarily should be done (although at least for normal official music videos I’d not want them entered as releases until we have a better way to show them in the artist discographies). But might be useful as a starting point for discussion.