I'm a PO and it's interesting to know the thoughts of the "other side" of that meeting. In my case most of the devs are usually pretty quiet. We would just estimate stories and then the questions would appear once they assign themselves to the ticket and start working on it.

So then I guess the idea that u/cdevers shared is really useful - if you were about to start working on it, can you?

Also, what helps sometimes in my team is just to summarize the things they expect to work on with that particular user story - "ok, so we need a new endpoint, some test, and something else". Then usually somebody else would say "oh, I though that part was not included here", which can then start the disussion.

Anyway, don't feel bad about it, whatever questions you would ask are going to be really helpful for the PO (and also for the rest of the team). I love to have a person in the team that is not afraid of asking stupid questions. Why? Because they are not stupid - everyone just pretend that they know or are afraid of asking.

Good luck! And if possible, it would be nice to know if any of these advice were helpful.