Is this Huawei phones as sold and subsidised by US carriers, like Verizon? Because AFAIK they're not bootloader locked at all, the ones I've seen anyway.
Everything sold in the US has a locked bootloader, including the Nexus. The issue is whether or not you can unlock it yourself easily here. With Huawei, HTC or Motorola, unless carrier restricted due to subsidies, you contact the manufacturer for your unlock code. That's how I've unlocked mine, it's no big deal, takes two minutes. I could almost do it in my sleep.
Verizon and Sprint are discontinuing long contracts and subsidies. Sprint never cared about bootloader unlocking, Verizon is the opposite and rarely allowed it. No idea how that's going to change moving forward.
While Huawei is the fourth largest smartphone maker and third largest growing in sales in China, very few people in the US have ever heard of them. To the best of my recollection, they've never sold a subsidized phone here - but they have sold models without allowing the bootloader to be unlocked and that's the basis for concern.
For example, you could import the Huawei P8 for use here, but you won't find it supported on their US website for unlocking.
I'm surprised that they sell all of their phones in China unlocked, but locked for the rest of the world.
And of course for those new to the discussion, bootloader unlocking has zero to do with carrier unlocking.