Hello Remy! Welcome to
So glad to have another themer joining the fun. Do take a look at the ThemeMaking Challenge
if you have time. It's a great place to meet other themers, collect feedbacks, and improve your theming skills.
As for the SPHERE theme, I already mentioned this. It looks great, and I really like the minimalistic view of it.
This type of theme is the best to use on a phone. Also love the background pattern and color scheme.