You're trusting a PO to decide on how you build? They ain't coders. They decide on value, you estimate and build and they prioritise based on the information you provide. POs aren't the boss of devs. That's usually engineering managers. You are both specialists in your field. You don't lecture them on value and how pointless a feature is, you size it, and using velocity they can anticipate how much will likely be delivered in next sprint. If they really object, "if you feel you can build it in 1 day, go ahead, ill give you access. I have no idea how that could be done"

PO wouldn't like it during live incident when shit goes wrong that you suggest "I did highlight the risk of this occurring and proposed mitigation steps but was overruled".