First of all, it's probably reasonably safe as is, especially since it is PTC-heater based.
Really the only thing it sounds like it is missing is a thermal fuse for extra, last-resort over-temperature protection and actual proper certification. Thermal fuses do seem to tend to die unnecessarily, prematurely when there is not actual fault in the product. Luckily they're relatively cheap and readily available so make for an easy fix, but to most people it just seems like premature product failure and another discarded item unnecessarily sent off to the landfill. Coffee pots always seem to be bad for that, I've changed dozens of thermal fuses in coffee pots in my lifetime.

Yeah, that looks like some generic Chinese import purchased through the Amazon Marketplace, rather than from Amazon itself, which would probably be more likely to be properly certified if were actually from Amazon.
If a product that plugs into the AC line really doesn't have a certification mark from one of the NRTLs (Nationally Recognized Testing Laboratory) like Intertek, CSA or UL, or have a special approvals or provisional approval sticker, it really shouldn't be sold in the US or Canada. I don't believe it is actually currently legally
required in the US, but a manufacturer or distributor would be insane not to get their product certified since if there's a fire or something, they would always be fully liable without proof of certification.
Current list of valid NRTLs for the US:
https://www.osha.gov/dts/otpca/nrtl/nrtllist.htmlSince the OP is the importer, though, you're likely the one to be liable for importing and connecting an uncertified product to the mains, and good luck going back after the actual manufacturer and supplier in China. That's the problem with importing random cheap, uncertified products from foreign lands.
Now, the thing is, I think this is appropriate. If I want to buy one of the nice 3000W British kettles and change the plug to use it here in Canada, I should be able to do that, but I also realize that I'm probably taking a chance at who is going to be responsible if the thing bursts into flames.

I don't want customs to be searching every imported item and telling me I can't import it because it doesn't have certification. There are many reasons I might want to do that, but if I actually use it I'd better be pretty darn sure it is safe, and use it appropriately, perhaps like not leaving said device plugged in unattended, etc. In the case of a British kettle, as long as I buy one that is good quality and is certified for use there, as well as watch for any potential recalls of that kettle in Britain, since they won't show up on recalled product lists here, I'm probably fine since it's the kind of device that is usually only used for a short period of time, while you're right there, then unplugged.