Have a look at my second example in the below reply. I think it covers basically the same use case as you are describing.
Any text value is fine, as long as it is unique per department.
Row Owners can be applied to any email or non-computed text column in any table.
Row Owners applied to email columns will always work.
Row Owners applied to text columns will only work if you’re using Roles and at least one user has a Role that corresponds to the text value. For example, if you’re not using Roles and you create a text column, fill it with the word “Admin” and then apply Row Owners to it - then no user will see any rows in that table - unless you also have an email row owner column in the same table.