How to learn from an MVP?

How do you learn properly from an MVP?

I made a prototype for an idea I have and currently I'm asking people who are in my target customer segment to try it out.

How do I gather meaningful feedback from them? The Mom Test (great book btw) stresses to ask questions that lead to non-biased answers. How is this possible after people know my idea/product? Many of the MVP-testers are friends and I feel like the feedback I'll get will be biased.

My success metric would be usage, so how many times did they use the product in the last x days. If I ask them directly I'm afraid that the answer won't be honest, since they might be afraid to hurt my feelings saying that they didn't use it.

One strategy would be to observer them using it. This is not really possible in my case (not an app or website).

Another idea would be to take the feedback with a huge grain of salt and adjust it according to my suspected bias, which means every lukewarm response is a negative response :D

What tips do you have?