What's a simple way for support staff to create Entra accounts?

Microsoft Forms backed by Power Automate is a reasonable place to start. Make the basic fields required, then have the flow check the submission and create the account with the standard attributes.

You could add HR and IT approvals before creation if those teams need to catch mistakes. Check that the automation can set your particular custom attributes before building the whole process around it.

A small front end calling an approved automation process gives you more control than asking support to fill out the full portal. Keep the form focused on things like name, manager, department, start date, location and the appropriate license profile.

Let the automation generate the UPN, check for duplicates and stamp the attributes. That keeps the fiddly decisions consistent while still giving support a straightforward form.

Is there an HR system that already holds the starter details? If so, take a look at Entra HR-driven provisioning before building a separate intake form. Whether it fits will depend on the HR system and what attributes you need to populate.

A PowerShell script doesn't have to mean a command line for the support team. A basic GUI in front of it could collect the inputs and give you flexibility over what the automation does. PowerShell Universal is another option if the approval and procurement process is worth it for your setup.