Just gonna add this here which is a quote from the last newsletter of Nitrokey titled "Nitrokey Partners With Purism to Build the Librem Key" which was just send out:

The Librem Key is a relabeled Nitrokey Pro 2 and except the logo both are identical. As you know, the device can be used for email encryption with GnuPG and S/MIME, two-factor authentication, file and disk encryption, and SSH authentication. In addition to that, the Nitrokey Pro/Librem Key serves as a part of the tamper-evident boot protection which Purism integrates into their Librem laptops.