I should better explain my use case:

I would like to create my own seed by using dice throws. When I have a 99 digit base 6 number, I want to type that into Bitcoin Core on an offline machine/live os. Then I want to take the XPUB that is created, and transfer it to an online machine running Bitcoin Core as "watch only". Then I can create new receiving addresses on the online machine, which I will also use to create PSBTs.

I don't mind using a simple script or two if absolutely necessary, but I prefer to only use Bitcoin Core for security reasons.