Strictly speaking, standout in the #termcap/#terminfo model is not necessarily the same as reverse video.

The Z shell's prompt sequences can only do standout, not reverse video.

Here's a #zsh 5.9.2 patch that adds %O/%o to prompts. (It turns out that the better letters were secretly taken.)

https://github.com/jdebp/slashpackage/blob/trunk/shells/zsh-5.9.2-JdeBP/package/patches/reverse-video.patch

Yes, I have been experimenting with changing standout mode to be boldface+italic. (-:

#Zshell