PTS says: If the practical test is conducted in the aircraft, and the aircraft has an operable and properly installed GPS, the examiner will require and the
applicant must demonstrate GPS approach proficiency.
Garmin says: IFR enroute and terminal navigation is prohibited unless the pilot verifies the currency of the database OR verifies each selected waypoint for accuracy by reference to the current approved data. (GPS approaches are not allowed with an expired database)
As easy way to verify the data is to check your approach charts amendment data against the GPS database currency date. If the approach has not been updated after your database software date then you are legal for enroute and terminal operations. So what's a terminal operation?
Google came up with this:
https://www.faa.gov/air_traffic/flight_info/aeronav/productcatalog/ifrcharts/terminalprocedures/
Looks a lot like approach charts in the picture. So, based on that logic, you should be able to use your GPS without a current database to substitute for DME if your approach amendment date is older than the GPS software date. Bear in mind, I'm not trying to do GPS approaches, just substitute GPS for DME on a VOR/DME approach.
Anyway, that's my story and I'm sticking to it. A conversation with whatever DPE one uses prior to the checkride would be a very good idea, however.
GPS approaches are illegal due to the expired software database but the 430W is still operable within the manufactures guidelines for other purposes. Would you placard the 430W "GPS software out of date, not approved for GPS approaches", and make a similar logbook entry?