PureBoot and the Librem Key handle those cryptographic functions using GPG signatures, so it may be possible to do so through the operating system instead. You can use this resource to learn more about PureBoot:
Yes, Tianocore is unofficially supported on Librem devices:
However, the Purism devices are no longer listed in the documentation, so I suggest directly contacting @MrChromebox if you want to pursue this option further: