You can use some of the debug items, as long as you're not like, trying to abuse the system. I mean you could drop in a strawberry and a snapdragon, raise them, and graft them. Just don't plop in a full cowplant. XD Or a whole set of fully-grown plants or something. But one or two items you couldn't normally get without leaving isn't going to break the universe.
As a rule of thumb, consider the following in regards to Debug Items:
1. Don't drop in items that will immediately fulfill an aspiration. (Cowplants, Collectible Sets)
2. Don't drop in reward point items, or otherwise difficult to acquire items. (Death Flower, Reward Potions)
3. Don't drop in completed craftables that you COULD craft yourself. (Workbench items, food)
Just use your best judgement.