Trek in Nepal most places have electricity facilities to recharge electronic devices by local hydropower and solar energy upon small fee which is fair if we compare remoteness. The common Europium Union etc. (not the 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 the same two round prongs. You can buy economical adapters in Kathmandu, perfect in size at the superstore next to the Nepal Spirit Adventure sales office.