If you aren't aware, your phone's screen can go much dimmer than the minimum brightness offered by the slider, if it supports HDR. There are apps that use an HDR screen overlay to lower brightness all the way down to the dimmest you can perceive. In my own experience, 'half' the brightness of 'minimum' brightness is plenty dark enough to not disturb sleeping at all if using my phone in bed.

Also for third-party monitors with MacBooks: BetterDisplay

Can even use an external keyboard’s native brightness buttons. Can still use f.lux if desired too though Night Shift maybe Sherlocked there a bit…