I'm actually a big fan of gnome! I remember watching the countdown to gnome 3 back in 2012. It felt like the modern next step for Linux desktops. But then they never made a straightforward way to add applets and extensions that didn't break every few years, and they have limited configuration options out of the box. I love the gestures and desktop management when I have 1 monitor, but that breaks down as soon as you add a second.
I still use gnome on my laptop, but I've always been a desktop andy. My desktop runs KDE Plasma at the moment, and it's so nice to be able to customize it in an intuitive and straightforward way.
One thing that I would recommend is to be curious! If they are open to it, ask questions about their journey and how it feels. Try to focus on them and their journey, and avoid asking questions about embys as a whole.
I came out to my parents over a year ago, and they haven't mentioned it or asked a question about it since. I'm moved out, so I only see them in video calls every week or two. Now I'm gearing up to bring it up again, and it's almost more difficult than the initial coming out experience was.
There are a lot of us, and each of us are different in our journeys, presentation, pronouns, and dysphoria or lack thereof. Some are bigender and some are agender.
Try to learn how to love them and help them to feel safe and grow into their best authentic self.