It sounds like a complicated question, which has a long and convoluted answer. It’s not.
Whenever there is a need to deliver a project or service, there will be people involved. The bigger the project, and the bigger the organisation, the larger the number of those involved is.
Pleasing everyone involved is, in most cases, unattainable. Nevertheless, the work must be delivered. Hence the need to pick just enough people whose opinions and sentiments matter, and then ‘managing’ them so that they support the outcome and provide the help that is expected of them. We call them ‘stakeholders’, as if everyone else is not interested in good results.
In an ideal world, if we had enough resources (and skill!) to deal with everyone involved in a project, there would not be so much need to identify stakeholders or manage them.
So, beware ‘stakeholder management’ in a small project - if you need it, then, likely, your project management skills need improvement.