The starting point is an image someone already rated

Day zero of a project is a tax: pick the OS, install the toolchain, discover what's missing at the worst moment. The image marketplace turns day zero into a search. Filter by OS, architecture, and community rating; most images are free and import to your library in one call; some ship with commercial software pre-installed, bought once from your balance and yours permanently. Create the container with container_image set, and the environment exists configured.

Then make it yours: add your tools over the terminal, snapshot the result with a permanent alias, and that snapshot is the template every future project copies from. Vagrant had boxes; this is boxes with ratings, a buy button, and no hypervisor underneath.