I have two of their U2F and if the OP's problem is sales and support, I'm not really sure Nitrokey are without issues as well:

1) Ordered 2, received 1. Thankfully, support quickly sent the second one once I wrote to them.

2) Now they only work when I plug something else to another port to my Mac (no such problem with Yubikey). No reply since April 29: https://support.nitrokey.com/t/nitrokey-u2f-issues-in-macos-...

Edit: I now noticed they have a different U2F version — the previous one was a card that you fold to make it into a USB dongle.