You can integrate an on-premises Workspace ONE UEM environment with a SaaS build of Workspace ONE Assist, in either single customer and multi-customer deployments.
The typical use case is that a partner with multiple on-premises Workspace ONE UEM environments (with single customer or multi-customer deployments) wants to add Workspace ONE Assist service. It is simple to integrate a SaaS build of Workspace ONE Assist to your on-prem Workspace ONE UEM build.