How about adding an auto-promote to queen when below 30 seconds option?

The auto-promote on premove option is great, but sometimes you can't get a premove in and having that popup in the middle of a time struggle is pretty killer.

It is a pity if you miss a minor promotion to a rook (like Saavedra) that wins or a minor promotion to knight that wins or draws. 30 seconds is halfway an 1 minute bullet.

I have never needed to underpromote on Lichess.

I do think a convenient way to access the setting in-game could be nice.

You could also turn on the setting to always auto-promote to a queen. In the rare case where you still wish to underpromote, you can hold down the Ctrl key while performing the promotion move and then it will always show the selection popup.

The usage of Ctrl to underpromote is also a bit problematic. Because it is almost never needed -- and the Ctrl key is not used in any other context-- it is easy to forget how to do it.
I remembered that there was a key, but I thought it was the shift key. If that happened in game it would be a bit annoying.
An actual key on the interface to quickly change those settings would be useful.

Actually a battery of toggle switches for Autopromote, Autodraw and maybe some others might be best.