You get ideas from everyone in your team. To know how difficult the hypothesis are to test, you can use the ICE score method where you use the points 1- 10 within I-Impact, C-Confidence, E-Ease.
- Impact. If this idea works, will it have a big impact?
- Confidence. How confident are you that this idea will work?
- Ease. Is this idea something that will be easy to test, or will it take weeks of product development to figure out?