For example, I’m using Debian, and I think we could learn a thing or two from Mint about how to make it “friendlier” for new users. I often see Mint recommended to new users, but rarely Debian, which has a goal to be “the universal operating system”.
I also think we could learn website design from… looks at notes …everyone else.
I installed Fedora on a system for the first time a few weeks ago and had a generally positive impression of the installer, but I think it was still unable to detect the existing OS on the drive. It was fine because I was wiping it anyway, but I definitely got the impression that it’s mainly designed for more simple use cases.