I think this is key. I often struggle to communicate that estimating certain tasks essentially means starting them and that giving a proper estimate might requi

I think this is key. I often struggle to communicate that estimating certain tasks essentially means starting them and that giving a proper estimate might require a day of work (or more), e.g. when getting familiar with a new API or working towards some performance criteria. However, this is rarely taken to heart so most of our estimates are more "if you actually want an estimate it will be essentially random from the top of my head", which satisfied the product owner for now and defers the dissatisfaction that comes when said estimate turns out to be inaccurate.