magic-wormhole doesn't need the initial configuration, but only lets you transfer one file (or one directory). So it's better for ad-hoc transfers, or for safely establishing the configuration data you need for a more long-term tool. The analogy might be that magic-wormhole is to synthing as scp is to rsync.
The snap/flatpak thing is weird, and I share your discomfort with uncertain provenance of software delivered that way.
I wrote the original version in Python, and took advantage of a number of useful dependencies (Twisted, to begin with), but a consequence is that installing it requires a dozen other packages, plus everything that Python itself wants. I've watched multiple people express dismay when they do a `brew install magic-wormhole` and the screen fills with dependencies being downloaded. If I knew Go, or if Rust had existed when I first wrote it, I might have managed to produce a single-file executable, which would be a lot better for deployment/distribution purposes, like wormhole-william provides today.