Yeah I would like separate buttons grouping Cantrips, 1st Level Spells, 2nd Level Spells... etc. The 2nd Level Spell window would include all your 1st Level Spells in addition for 2nd Level Spells for the sake of upcasting.
Also an option to bind specific spells as we do now so we can quickcast spells we use frequently (e.g Eldritch Blast), but also the option to bind specific spells with a window to choose level just as OP suggests.
Whilst we're on the subject, a minor QoL life regarding Hex: have each Ability use a different colour in the window to make selecting the correct ability quicker (e.g Strength=Orange, Dex=Yellow, Con=Red, Int=Blue, Cha=Purple, Wis=Green)
