They most definitely do need Apple's approval. Especially since El Capitan. The OS won't allow any extension to load that isn't code signed. And getting approval from Apple to make any part of an app an extension is very difficult.
I wouldn't worry about it. This whole idea that Huawei is now somehow evil came from the notion that they hold majority of patents (32%) of the upcoming 5G network. Our current administration has gone way overboard in demonizing anything that doesn't say "Made in USA" on it. According to one article I read:
The CIA and NSA hacked into HuaWei and stole tons of information over the years but found no evidence of HuaWei spying on their customers or end consumers. Also they found no links with the Chinese military or Chinese government at all.
Is that conclusive? No, but there isn't any way possible for the U.S. to be 100% certain tech from China, Russia or other nations don't include spying capability that isn't supposed to be there. No more than they can be certain American made computers, security cameras or whatnot don't contain the same.