Most companies could chop an entire layer of middle management, perhaps many layers, and get an instant boost in productivity and happiness. I wonder if there’s any mechanism for workers and senior management to make this happen and share the rewards.
1/3 is in service of the team. Some of this is bureaucratic (approving expense reports, hiring/firing/promoting), and some of this is being a team facilitator. In meetings, watching that everyone is talking and that one person isn't dominating. Helping with conflict management. Pulling together people from three teams for a meeting and leading it.
Again, that's about 1/3 of the job. Half of this could be done by team members, but these are skills that require knowing tech but aren't tech.
1/3 is getting senior management what they need. Does the project need another developer? What is the high level status of the team? Is there technical debt that needs prioritizing that requires more than what the individual team can commit to? These are things that can be done by developers, but it's going to look a lot like what the manager does, and someone is going to be pulled off of more and more development work to do these.
And the last third is to the rest of the management team. These are the work to make the department run that people don't notice.
I worked at a place that had a very lean management:worker ratio, and instead developers ended up doing a lot of the management work, effectively becoming managers without the pay bump or recognition.