Examples for minigames: a greenhouse which lets you plant and harvest things, a workshop for crafting new instruments, or an arena with a deckbuilding aspect from instruments you collect or craft.
They would need to be carefully constructed and synergized with the existing areas, so you’re spending an equal amount of time exploring the universe as your internal world. One way to do that is for there to be secondary resources, which are unique to the reach and the cellar, but both necessary for some crafting system that has multiple tiers of refinement and uses. But there might also be a third one specifically for transforming one into another, as a way to respect your time and interests.
Is this the perfect premise for those things? Not within the original vision released here, but possibly as a grander rework.