Trek in Nepal most places have electricity facilities to re-charge electronic devices by local hydro power and solar energy upon small fee which is fair if we compare remoteness. The common Europium Union etc. (not UK) two round pin plugs model work in Kathmandu and trekking but with a wobbly fit, Nepalese and Indian outlets are just over an MM wider. If you have an Apple USB charger the “big” model, you can swap the duck head or use a standard cable that ends with same two round prongs. You can buy economical adapters in Kathmandu, perfect in size at the super store to next to Nepal Spirit Adventure sales office.