On-Demand Development Environments

Tools to create reproducible development environments are basically everywhere these days, from Development Containers to Nix wrappers to questionable Docker hacks. However, all of these (that I have found) have a common flaw that bothers me: they all require eagerly fetching the entire environment to get anything done. This kills the premise of these environments providing any easy on-ramp for users when the first step is to download GBs of binaries. Across projects I work on, we have probably 5-10GB of dependencies, but its extremely unlikely a single developer will use more than a fraction of these at a time. Even for repeat contributors, updates to these are not always incremental (though some are), bringing continued pain as time goes on.