I think once you're into anything less than 60%, either you literally just type text and use the mouse/touchpad items instead of keyboard shortcuts, or you're more focused in the aesthetic minimalism rather than the functionality.
I don't have to take my hands off the keyboard to do stuff like navigate text simply, pause/mute music (instead my pinky goes to the bottom of the keyboard and all the keys on the other hand change function), my software can all be driven from the "common" keybindings and modifiers like ctrl/alt/win are on my thumbs instead of being offset below my pinkies.
Importantly, i can throw it in my bag with my laptop and use it when i am traveling so there is very little context-switching that has to occur.
None of this really carries over when I boot in to windows, though, and I keep a ten-keyless keyboard around for playing video games.
Maybe if the bag was filled for plane travel that'd be a problem.
That said (author here), I actually use a 65% for daily use. The 40% was too small for me to use comfortably. I could get used to the caps lock for arrow keys and text editing stuff, but having to remember shortcuts to type a semicolon just wasn't for me.
The switches felt great to use (chosen myself), the keycaps were still easily customizable to an office-appropriate yet imo stylish theme, and the default layout was intelligently designed to where most functionality was already within reach of your fingers.
Functionality would be in 'layers'. While they're usually numbered, I think of them as 'Alternate Shift', where normal Shift is 'up 1' (CAPITALS, and !@#$%^), and other layers can be whatever you want, i.e. `Layer2 A` = "{", `Layer2 S` = "}". The layout is set by the (often customizable) firmware.
I stopped using it when I changed to a 100% remote job, but keep it as a display piece.
Just adding effort to add additional keys using capslock.