It's pretty standard to have Escape open the "menu" and would have been reassuring when I was trying the various interface types and was wondering why right-click for commands "stopped working". (I'd changed to Verb Coin, which switches from right-click to left-click-hold. Another weirdness.)

There are a few hotkeys that open various menu pages. The most accessible one is probably the TAB key.

The reason Escape can't be used it because it's reserved for making the player character skip to their final destination instantly, when walking/running.

I would have thought that'd be double- or triple-click. (Triple since apparently double is run.)

Regardless, it could still bring up Options or Save/Load when it has nothing to cancel and no movement to skip.