Simply having Favorite Groups, or being able to set favorites to be pages even if not Full would be an AMAZING feature.

Having a group or page for ex.
[Create - Item] [Create - Fluid] [..]

Or even just
[Item - Transport] [Fluid - Transport] [Filter] [Machine] [..]

Instead of having to do a million searches, adding singular Item's to the favorites, then having to sort trough them is hella tedious. This could make it easier. Exporting the favorites afterwards[i know different feature, most likely doable by copying config], would make this even a carry bag to other modpacks to find the stuff you usually need much quicker than having to scroll your eyes over hundreds of Items and having to remember all the Names.

This could be expanded even more, if we had Main Groups and Sub Groups. Main Groups could be selectable in the Interface of sidebars.
This is NOT the Subset way in the past, but could be fully customizable to the user without text config.

Really hard to explain but there is a lot of potential in this. (Items do not exactly Match Groups in these, it's just a quick example)
[A]

[B]

[C]

A lot of potential, depending on how it's implemented, maybe needs some dev time. Huge request.