This, but also some way to search for items for sale in user shops. This could either be done using a marketplace where any item being sold by a user shop is displayed with a price and can either be bought straight from there or you are redirected to the user's page. Or perhaps a more general search function that, when searching for a particular item in user shops will bring up a list of users currently selling that item.

Additionally, please PLEASE include a confirmation window when purchasing items from user shops as some of us have tap-to-click enabled on laptops or are on mobile and may accidentally click the buy button.

I also agree with the idea that the watering needs for plants should be more forgiving, such as needing to be watered once per 24 hours and having some sort of timer as to when the plant needs to be watered again, or offering an auto-watering feature that is paid for in PC or SPC for a week/month long service time.

Also, as has been mentioned before, perhaps some sort of "inventory sell" feature to sell unwanted items at a fixed price back to the site as a way to make a little bit of PC at a time instead of having to straight up destroy or combine items to make space. I don't think this one is too necessary, especially since we don't yet know how hard or easy it will be to get PC, but this could be a goof feature as an extra source of introducing PC into the site if needed.