Because the subject was LiFePo I assumed your question was about Lithium batteries generally, not the actual company.
They look legitimate. They have an online presence and reviews of their other products are generally positive.
That said, the price is a little suspicious, less than 90% of comparables.
The spec sheet is squirrely. There's a general lack of information on the batteries and it makes me wonder if these might be factory rejects-that is, cells that didn't meet their original design spec and are being sold at a derated spec. Happens all the time in manufacturing though I don't know enough about these batteries to say that's a thing. And, I'm not sure it would be a bad thing because maybe they have greater capacity, and are just sold as lower capacity. All speculation. It would be easy to confirm with capacity testing, so if you buy them that is something to check.
The other thing is since you are not building this battery you won't know if the cells are balanced from the factory. You'll need a BMS and I'm guessing you'll also need an active cell balancer, which is an extra hundred bucks but will help you squeak every amp out of these.
A lot of money to put down for a 10% discount, without an Amazon guarantee.