Don't buy a new charger, just buy an adapter.
I have the Huawei Mate 20 X EVR-L29 (international version) & the seller threw in an adapter with it for free so it fits US sockets.
I will take a pic of it & post it when I get home.
I bought it on eBay.
You can buy it off of eBay & Amazon.
I don't know if WiFi calling works, I never used when I had a post paid plan & I don't think it's an option with prepaid plans.
I don't see why it wouldn't work.
Everything else works perfectly.
I am in the US, I'm in Atlanta, my Huawei Mate 20 X EVR-L29 works perfectly for me, I get perfect 4G LTE on AT&T network, I've no complaints with this phone.
It's hands down the best phone made thus far !