@Jandalf I recently had to reset my System Integrity Protection settings (csrutil clear) and once again ran into this issue, where my Razer device was not recognized.
I have upgraded to macOS Big Sur 11.1, and I can confirm that the solutions by @avaddon and @rdabban, which had worked for me on 11.0, no longer work.
Manually loading the kernel extension (the kextload command) will display the error code 27 "Extension with identifiers com.razer.common.razerhid not approved to load. Please approve using System Preferences.", but no pop-up or "Allow" option would appear anywhere on the System Preferences.
Adding the Razer TeamID with the /usr/sbin/spctl kext-consent add R2H967U7J8 command showed me a pop-up, but with no "Allow" option, and no option to allow the kernel extension would appear in the System Preferences, so no good.
I finally managed to make it work by temporarily disabling System Integrity Protection (SIP), as follows: