1 - Empathize & Define
Use the LLM as the oracle that you need to interpret its statements to understand the problem that your product will solve.
2 - Ideate & Prototype
Use the LLM as your design team that will ideate and build a quick an dirty prototype of your product.
3 - Test
Use the LLM as your client or test group or anywhere you get feedback from in order to evaluate your design.