I don't feel that an organization like that is the best way to run a company. It may be a superior way to the reality of most companies today, but that reality makes achieving an environment like that extraordinarily difficult.
Here's the reality I've seen: PMs and EMs share a very similar domain of responsibility. The "20% work" of both jobs is different; but 80% of it isn't; its communication and defense from the rest of the business, and organizing the work the engineers need to actually do. Who actually does it, in your org, the PM or EM, depends on who has more political capital between the two, which is something of a function of their skill level, experience, and ability to market themselves. Great EMs look like PMs. Bad PMs do all the bad things bad EMs do, like micromanage.
Phrase that paragraph another way: in most orgs, in my experience, the PM role fills a need which arises when the team makes a sub-optimal EM hire, and vice-versa.
That's my reality; but the obvious problem with that reality is, if you look at the scientific, hypothetical definition of what a PM should do, its not that. There's tons of more product-focused "we want to build the best thing" kind of work that feels, to me, rare for even Fantastic PMs to actually get to do because they're compensating for an EM that isn't pulling their weight. Vice-versa, if you have a Bad PM it might not even occur to them that this "we want to build the best thing" class of work is a fundamental part of the role; ZIRP document factories that could basically be replaced with an LLM trained on all the meetings they've attended.
The additional lingering problem is that, part of that 80% work, "defense against the rest of the business", depends significantly on the rest of the business stepping back and creating an environment where this "unit" (the EM, PM, and engineers) can be autonomous; and I've also nearly-never worked anywhere where this was the case, even leadership that says "its y'alls call, you've got authority in this domain" inevitably catch wind of some decision they dislike, for reasons rarely more substantiated then "it feels wrong", and even a small number of torpedoes like that can seriously, seriously harm an entire team's feeling that they're allowed to go on of the offensive, rather than playing defense 24/7.
Point being: The single best characteristic of upper leadership, its not close, there's zero argument of this in my mind, its not technical ability, business experience, good talking skills, domain experience, whatever: Its Hiring. Being able to identify strong talent, keeping a pulse on the performance of that talent, ground-truth, all the time, and being willing to let people go if mistakes are made. But, what I've just described is extremely difficult to execute effectively, because every actor in this game is self-interested and will actively misrepresent the performance of themselves and their unit; politics is the hardest game in the book.