OmniSupervisorConfigUser is the object/entity where Salesforce Omni-Channel Supervisor Configurations Users assignments are stored. So, we have to query the OmniSupervisorConfigUser object/entity to fetch the Salesforce Omni-Channel Supervisor Configurations Users assignment.

Sample SOQL:

SELECT OmniSupervisorConfigId
FROM OmniSupervisorConfigUser
WHERE UserId = '0057V000009PVQA'