> Having ff on an ipad and phone is really not having a “common point of failure”

The “common point of failure” is GPS, which does have regular local/regional outages. Your instruments may be able to use VOR/DMEs, and hopefully you're able to use the VOR MON:

* https://www.flyingmag.com/flying-the-mon/

* https://www.faa.gov/air_traffic/flight_info/aeronav/acf/medi...

But if you're relying on a GPS approach, you may be SOL (many places don't have ILS, and only visual and GPS).