Travis is correct. Limited is required for even read-only access to most applications. Self-service entitles customers to use very specific applications (like the View SR application). Read access to any other applications (SR, WOTRACK, ASSET, etc.) requires Limited.
We allow reports to be emailed or the Maximo database to be connected to external reporting tools (such as Power BI) without needing licenses for those users. Depending on the use case, it might be better to expose this data in an external reporting tool.