A positive thing you could do is to continue to learn about the experiences that AuDHD people have and productive ways to support them. If you understand the challenges she has it will be easier to be patient when she has difficulties. This may even lead to an understanding of how to effectively communicate the idea to her in a way she doesn't immediately reject.
Worst case, you grow your understanding for a large group of people that frequently have difficulty functioning in society.
I would personally use Debian as my first choice then use Ubuntu if there is a reason to use it over Debian. For example Ubuntu will often integrate drivers for new devices faster than Debian. But if you are dealing with hardware released more 1 year ago, I wouldn't worry about that. Also, some applications will specifically call out Ubuntu as their supported distro.