A balance of power between engineering and product ownership is a terrible idea. The role of engineer doesn’t necessarily require any understanding of the customers needs. If you have an engineering team that understands them well, it’s either because of competent product ownership, or it’s a complete coincidence. Engineering should not have control over what is built, or have the power to override product owner’s decisions. Product owners should not have control over how things are built, or the ability to override engineering leadership’s decisions. They’re simply different areas of responsibility, there is no need at all for a balance in power between the two, and creating one for the purpose of avoiding bad decisions is just as likely to be used for avoiding good decisions, or decisions that conflict with somebody’s personal taste or political objectives.

Deciding what to build, and for how long, indirectly dictates you how things are built.

Deciding which engineers should have a career advancement also influences how the product is built.

It sounds like you’re describing your own experience of office politics more than anything relating to the roles of product and technical leadership.