2. Keeping the language pythonic, without any additional need to learn a DSL has definitely been key to Metaflow's adoption internally. That said, this is something we are open to hearing back, esp. with this OSS launch.
3. Yes - definitely think so. Personally my favorite is the local prototyping experience part; when everything can fit in memory and is blazing fast. There is an also an open issue for fast-data access, which you can upvote if interested in seeing it open-sourced.
4. We don't think there is an exact equivalent as well. :)