@Ariel_Rokem Such a use case is exactly the purpose of the (now somewhat elderly, needing more documentation some overhaul, but should work) https://travis-ci.org/github/datalad/datalad-crawler/ extension (just pip install datalad-crawler). With that one you just would end up with 2 stage procedure (so your fancy_command == crawl-init + crawl and it is not direct datalad install although probably could be made into such for some use cases). Unfortunately, we seems do not have a nice tutorial for it in the handbook yet. But there you can find my earlier response which outlines typical use case : How to crawl with datalad? . It is with the datalad crawl we got and keep updating (from time to time) many datasets on http://datasets.datalad.org/ which do not natively come as DataLad datasets.
There is also datalad addurls which provides a powerful tool for populating (and somewhat updating) datasets (or even hierarchies of them) from some structured (.csv, .json) data. Eventually someone should overhaul (or actually just provide an alternative pipeline within it) to use datalad addurls functionality, and just feed it with those structured records crawler discovers.