Hi @K3nzo, welcome to the Supernotes Community 
You’re totally right, additional themes has been mentioned a few times over the years. I’ve actually just combined your post so everything is together 
– if you reply to old topics it will promote them to the frontpage.
Adding more themes hasn’t been top priority mainly because our color palette is v. large and there hasn’t been much interest since we generally offer more themes than most out of the box. However additional app icons will be coming soon to mobile.
If anyone else would like additional themes, please like @clefshanty original post above so we can gauge interest 