How are days worked in OR reported in Turbotax for a Washington resident w/ an Oregon employer w/ a telework agreement? Are holidays/PTO exempt from OR tax?

For the days worked in Oregon, you would look at any day (or part of a day) that you were physically present in Oregon.  Usually the holiday/PTO hours are not counted, or counted on a percentage basis.  You can make the adjustments if needed for income tax purposes.  Your employer has obligations to the state of Oregon for income tax withholding, see Remote Work Agreements.