I'm "secretly" pondering a formula where a group of employees share an assistant rather than a manager.

In stead of a layer of management above the people manager the assistants also share an assistant.

With a small salary comes a rigid job description without free styling.

1-4 times per year you bring in a consultant/freelancer to read the reports (AI generated abstractions) and twiddle the knobs for however long it takes. Say 1-2 weeks with nothing but meetings. It should probably involve a hotel, resort or boat trip.

How do you manage hiring and firing from the team?

That's ultimately why Managers wind up "on top", they can make choices about who to bring on, and who to let go.

And since they are "on top", they say they deserve more money and more control, etc.

You're half joking probably but this is what a manager should be. Someone who enables you, not someone who makes your job hard.