COS, Nov 1992, snowstorm but above precision approach minimums. Me as PF using ILS. After passing outer marker the LOC and GS needles started going awry. Slow, erratic meandering is my best description. Not like my normal foul-ups. Went around. Tried again, FO flying, me NF. All well until nearly to MM, then happened again. Went around again, and as we did I noticed pax behind FO was using cellphone. Told him to turn it off and keep it off. Next try, me PF, LOC and GS worked correctly all the way. I reported it to mgmt, as per company rules; don't know if it was ever reported to FAA or FCC.
Granted, this is only ONE example and it was a long time ago. But it happened to me. Technology changes so I don't know if it would work the same on an airliner today. There's a procedure for checking devices before approval. After they do the checks required, fine, they can allow operation of whatever has been proved to work. And I'm sure that's what they do. But when I am PIC for IFR, any non-FAA-approved PED on which I did not personally do the full inflight EMI check must be off. Your mileage may vary.