If "I know" is a shade too far or just too much try a more neutral version like, "okay".

I've adopted "okay" as a canned response to these interactions with men. It's been incredibly freeing and anxiety reducing. Definitely, being in public space is less stressful. Not stress free, but maybe we'll get there with the other stuff that happens in public.

At any rate, "I know" and "okay" are excellent checks to intrusive male behavior in inappropriate places.