Very interesting project! I love the web-compatibility goal.

One thing that would help there is support for bare module specifiers via package name maps: https://github.com/domenic/package-name-maps

This would allow for imports like:

import * as _ from 'lodash';

Without any requirements on a specific package manager. It's our hope that npm, yarn and others will produce package-name maps during installation, giving you a bridge there. We have a reference implementation in progress here: WICG/import-maps#37