I would drive via Geilo and take rv 50 to Aurland. From Gardermoen to Geilo there are plenty of chademo (Fortum and Grønn Kontakt).  In Aurland you can charge on Artic Road  charger. Drop in is very expensive, so consider buying a month subscription. In Flåm you can ask the camping if you can charge there.

Back from Aurland to Geilo is potentially a problem.

The shortest way is rv 52 Hemsedal, but you would have to drive from Gol to Aurland without charging.

Later this year many new chargers in this area will open.