Can we set a model condition to show records owned by any public group the owner is a member of?

Usually we are filtering records where the owner id is the sf user … we have several use cases where we need to show records owned by the salesforce user as well as records able to be viewed by public groups they are a member of.

Any ideas on how to state this in the model conditions?

You may have to create a model on the GroupMember object to get a list of the groups the user belongs to, then, in your primary model, add a condition that restricts the results based on the owner of the record being in the Group Id field on the GroupMember model. Then in the condition logic, you would set it to display records that conform to either condition 1 or 2.