They are maybe lying, but one of their latest tweets talks about a waiting list with over 100.000 people waiting for a Ledger Stax. Even if half of that is true, it's still a lot. You should never underestimate people's willingness to purchase stuff they don't need. I see no reason to purchase either Stax or Flex, unless you want your NFT's to be visible even when the hardware wallets are turned off on multiple devices. 
They recently made a few tweets about trying to fix the problem of blind signing. The link to the product description you shared mentions, "What you see is what you sign", but I don't that's it. Also, it's a software feature that doesn't require the release of a new device.
They recently made a few tweets about trying to fix the problem of blind signing. The link to the product description you shared mentions, "What you see is what you sign", but I don't that's it. Also, it's a software feature that doesn't require the release of a new device.