I find itch.io to be a great resource not just for games as a "finished product" but for prototypes as well. The regular gamejams contribute to this - a platform of many prototypes. They don't need the polish and coherence you'd want to invest and publish on Steam.
Have you considered publishing your prototypes?
Even as only a player, some prototypes make for very interesting playful exploration, even if it's short. For a technological, creative, and inspiration they can be a treasure trove as well.