It's really a good one!
I skip boiling an onion though as I've honestly never noticed it being used in parts of Thailand I've been to.
Also you can easily replace a coconut oil with an olive oil and a coconut sugar with any raw and moist type of sugar. I use raw cane sugar, it's very moist and soft and not as sweet as usual types. This soup is very coconuty even without using everything coconut.
Adding about 5 slightly crumpled kaffir lime leaves brings more of this wonderful limey aroma so if you have some on hand you can absolutely try it.
Green curry paste works perfectly fine don't even panic if you can't find a red curry paste.
You may also want to boil a small amount of any white rice like jasmine rice as a side dish because I've noticed my family tends to get hungry quite quickly after enjoying the soup.
All in all this tastes quite authentic and I totally recommend trying it out!