I had a kind of... manipulative co-worker who often tried to work around the Product Owner. He'd come into my office and ask, "Can we do <some feature>?", hoping to trigger my inner engineer to be interested in how to solve that problem.
He finally got tired of me saying, "Given enough time and resources, yes, we can do pretty much anything! Talk to <Product Owner> about what we SHOULD do."
He finally got tired of me saying, "Given enough time and resources, yes, we can do pretty much anything! Talk to <Product Owner> about what we SHOULD do."