How can you view an isolated hidden category for "balance" purposes? (re: reimbursable work expenses)

If you just want to track and see how off $0 it is, you can add the Transaction Tracker for Google Sheets to your sheet. Then, select Work as the category and unfilter hidden.
However, you might want to consider not hiding these. I do similar and have a $0 budget, but they are valid expenses and then valid income that I do want to see tracked. If I report on just that category, then it should be 0.