Assign Permissions To Certain CMDlets for powershell?

I've never seen a way to do this and I honestly can't imagine the complexity of implementing something like this.  Like you said, the actions of the various cmdlets are controlled by the users permission to Office 365.

Limiting what cmdlets people could use would be the equivalent of limiting permissions in the Office 365 admin center on a link by link basis.  Not something that would really even be feasible to do (or easy to manage).

The only way I've come close to something like this is by building my own "front end" for the actions.  At a hight level:

- Create a SharePoint list that a user has access to (let's say a list for adding people to that need a specific O365 license)

- Trigger a flow when a list item is added

- Launch Azure Automation as part of that flow

- Run the specific cmdlet(s) to assign license within an Azure Automation runbook using credentials stored in Azure Automation and parameters past from the list to Azure Automation via Flow

this would allow you to grant people access to the list to assign licenses without having to give them any rights in Office 365 Admin Center.