The Z Fold inner screen is nearly 8 inches and also it supports the S Pen which is a useful feature for Goodnotes.

P.S. also, support for Galaxy S lineup? The Ultra also supports the S Pen, and iPhones support Goodnotes, so what's stopping it from being compatible with the Galaxy S lineup which has larger screens than most iPhones.

P.P.S. Samsung phones (S and Z Fold/Flip) probably have a lot of users than the S Tab, so expanding Goodnotes compatibility to Samsung phones would potentially increase beta users.