I think it'd be neat to add a feature where the inventories of item shops are randomized. In addition to the usual Red Potion/Heart/Bombs, could also sell multiple Heart refills (like, 5x hearts, not just one), Arrow packs, Magic Refills, Green Potion, Fairies, and maybe Bomb and Arrow capacity upgrades.
#Random Shop Inventory
sage linden
grim briar
this is a feature that's implemented in the rando, but not exposed on the main site - it is available for use in the #door-rando branch, which can generate seeds without doors shuffled as well, info about that implementation here: https://github.com/aerinon/ALttPDoorRandomizer?tab=readme-ov-file#shopsanity
snow zodiac
In fact there are multiple independent implementations of Shopsanity. There's the one in DR as mentioned above, which puts all the shop slots in the pool, and AP made their own version that is more customizable. With it you can shuffle the basic shop inventory of supplies, and also add a configurable amount of pool slots in as well, which after buying will reveal a supply available as well. You can even make it so that you have to pay non-rupee resources, such as hearts, to buy things.
There's an easy way to generate DR seeds here: https://avianart.games/customizer