Ubuntu 18.04 - Second monitor couldn't be detected. Using Nvidia-430 form ppa:

Problem is, your AMD gpu is too new for the currently running kernel, you’ll need kernel 5.6:
That one is probably compiled with gcc 9.3 so the nvidia driver wouldn’t compile with it on 18.04. So rather install 20.04, then the 5.6 kernel, afterwards the nvidia driver 440 using Software&Updates.
Afterwards, please follow this to get the nvidia gpu running:

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