Hello FranzOren,
sounds like you are a keen hacker. I think a lot of hackers have autism.
I haven't time to read your earlier posts. Do you end up "bricking" some things? Do you have enough back-up and hardware to survive that?
I know that Ubuntu is derived from Debian, and they use the same .deb packages. I think Ubuntu would change a lot of architectural and configuration files, like stuff in /etc and /usr, and symlinks might get trashed or dead-ended. I guess this is why straight replacement doesn't work. I think Ubuntu's snap app store thing also creates more divergence.
I wonder, are you trying to avoid dual-booting?
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Precontemplative.