If you ever find that an artist on other platforms isn't on Bandcamp, you'll usually find them on Qobuz's Download Store since that's a common place that they also tend to publish.
It's a little less convenient than Bandcamp, and is often a little more randomly priced across artists and even individual songs from an artist, but if your goal is to compensate them and get a high quality audio download, it'll be another option.
They also have a streaming offering with way better payout rates for artists at what tends to be around $0.01873 per stream as of last year, in case you're not ready to ditch streaming, though I can't speak to how good it is as I haven't tried it myself.
Actual downloadable software or just a website?
I've heard of Soundiiz before for migrating playlists to something like YouTube, though it's paid for larger playlists, and after that yt-dlp will work well for the now non-DRM protected playlists on sites like YouTube Music, but not on DRM-protected ones like Spotify, or ones that only show samples by default like Deezer.