I'm currently charging the Air M1 off a 20W Anker Nano which is kind of amazing it works for a 30g device although it charges very slowly but is quite handy to drop in your bag in case you run out. I've ordered a 45W one but they are out of stock presently.
(https://www.amazon.co.uk/Charger-Anker-Durable-PowerPort-Inc...)