There is a default owner field present on the Opportunities module next to the CRM score. If a customer wants the 'Owner' field to be added as a grid, we can inform them that it is already present and what is the requirement of another field.
If the customer wants the 'Owner' field to be filterable, do not make the field filterable from app builder.
Instead inform the customer that there is a feature on Clari called scope.
Customers can filter 'Owner' based on the options provided or also Customise based on Role and Owner.