Have you ever considered leading your boss? What your boss, maybe every boss, needs is a fellow traveller to notice what they did well, to suggest a next step, to console, and to consider a possible ‘plan B’.
Make sure you don’t tell them you are mentoring them or leading them. Instead take yourself out of your appointed role from time to time and instead of “speaking truth to power” consider your own power to speak to a fellow struggler, a fellow traveller, a fellow person who is doing the best they can at this very particular moment.
They are just like you with all the fears and chaos and worries that you have. They might just need you to be their “boss whisperer”!