I have yet to see a company where the "loyal" employees are paid more than those who leave for a better salary, or are exempt from laid off. I feel like "Company Loyalty" is one of those nonsensical ideas boomers left to the younger generation.
Companies provide some value for employees that they don't get back from them, and vice versa.
Employers can "demand" loyalty, but as you say, it's basically a request. There's no legal basis for it or anything.
I think it's fine to have a culture of loyalty. It probably means you have a pretty good company. Demanding it doesn't work, and if it's not real loyalty, we don't have to be mad about it being one-sided.