No they aren't. There are no statutes of any kind requiring a public company to maximise shareholder wealth or value. It's an oft-repeated fallacy, a myth, a load of utter nonsense. Apple was a public company even when they were failing badly. Michael Dell publicly suggested they liquidate and return funds to shareholders just before their big return. They'd been spunking reams of money on bad products - if they were required to maximise shareholder wealth then (as they must have been if it were true) their board would've been in trouble.
Many public companies' executives will feel the need to try to do that of course but that's typically to make themselves their fortunes, or stave off any threat of replacement by the board or via institutional investors.
So no, they are not some slave beholden only to enrich the stockholders. If they (s/h) don't like what the company are doing at any given time they can raise a concern, call a meeting (if they have enough %age support) or they can simply sell up or shut up.
I see this so much it makes me cringe. If it were the case you'd have execs going to jail on a regular basis for daring to spend R&D money on something that flops afterwards.
New macbook didn't even appear so we don't know if there will be or not version with dGPU and competition (Asus, Dell) have dGpu options.
