Source? I've installed Ubuntu on half a dozen newish UEFI computers, some of which came with OEM Windows, over the past few years with no trouble https://wiki.ubuntu.com/UEFI/SecureBoot
[1]: "On Ubuntu, all pre-built binaries intended to be loaded as part of the boot process, with the exception of the initrd image, are signed by Canonical's UEFI certificate, which itself is implicitly trusted by being embedded in the shim loader, itself signed by Microsoft.
On architectures or systems where pre-loaded signing certificates from Microsoft are not available or loaded in firmware, users may replace the existing signatures on shim or grub and load them as they wish, verifying against their own certificates imported in the system's firmware."
[1] https://wiki.ubuntu.com/UEFI/SecureBoot#How_UEFI_Secure_Boot...