How to identify users handling SITs before purchasing Microsoft Purview licenses?

Posting this on behalf of a customer we are currently advising as a Microsoft Partner.

The customer is in the evaluation stage of Microsoft Purview and has raised a licensing concern that we would like the community's guidance on.

CUSTOMER'S CONCERN

Purview licenses are user-based, meaning every user who directly or indirectly benefits from the service needs to be licensed. However, to determine which users actually handle sensitive data (and therefore require a license), tools like Content Explorer and Activity Explorer are needed — both of which require an E5 or equivalent license to access in the first place.

This creates a chicken-and-egg problem for the customer:

They need Purview to identify who handles sensitive data, but they need to know who handles sensitive data to decide how many Purview licenses to buy.

QUESTIONS ON BEHALF OF THE CUSTOMER

1. Is there an official Microsoft-supported mechanism or tool that allows customers to assess their SIT exposure and identify affected users before committing to a full Purview license purchase?

2. Is it viable for the customer to purchase a single license (1 qty) assigned to an admin account to perform a tenant-wide scoping and discovery exercise — and would that single license provide sufficient access to identify all users handling SITs across the tenant?

3. If the 90-day Purview E5 trial is the recommended path, does Content Explorer automatically scan and surface SIT matches across all users in the tenant without requiring any pre-configured DLP policies or sensitivity labels to be set up first?

As a partner, we want to ensure we are guiding our customer toward the correct pre-purchase assessment approach before recommending a licensing SKU and quantity.

Any guidance from the community or Microsoft would be greatly appreciated.