shortcut to adjust screen brightness according to Voiceover state?

As far as I know, there's no way for Shortcuts to know if an accessibility feature is active or not. If anything it'd have to be an automation trigger, and it definitely isn't one.

The closest you could come would be to create a shortcut to turn voiceover on and one to turn voiceover off and include the screen brightness setting in that, but you'd have to use those shortcuts instead of the built in ways to turn VO on and off.

Well, you could speed it up by just creating a shortcut for 0% brightness and one for 60% brightness and calling it something memorable. Then you could just ask Siri to do it or even one of those new vocal triggers if you're running the latest iOS. At least that way you wouldn't have to muck around in control centre or something.

Would Screen Curtain maybe meet your needs? Just set screen brightness to 60, and use Screen curtain whenever you are using Voiceover. It would be the same as having brightness set to 0.
I just tested, and when you turn off Voiceover, the screen curtain also turns off.

Just a thought.

Well doesn't screen curtain do that already?

I have just a little vision, but from what I can see, it turns the screen black. If there's any brightness, it's less than 5 per cent, but probably 0.
I can't say for sure about the battery setting, but you could try it for a day or 2, and see if you get the same results.

Todays camera do not need to have the screen made brightest. The camera is able to make sure that the picture is a good one. You just need to make sure the setting for it are the one you need regarding quality of the photo. I always have my screen setup to adjust to the brightnests outside and when I need a sighted person to take a picture I just turn off VO and no issues.

My screen brightness is always set to ambient lighting. I always use screen curtain with voiceover, and if I need someone to take a picture of something for me, I just turn off voiceover and voilà all is good to go.

Just ask Siri to set it to a percentage before you turn off Voiceover, nice and easy, and no fiddling about with shortcuts.

Then the only thing to worry about is how it adjusts the brightness automatically.

If screen curtain is on, it will stay at the last percent it was at before you turned on screen curtain, and you don't need to see to find that out, just look at the slider in the display settings.

Screen curtain doesn't set the brightness to 0, so if that's on but the brightness is still up, it will still drain your battery. I found that out the hard way when I forgot to turn the brightness down from 50 after having a sighted family member doing something on my phone. I wish there was something like you're suggesting because it's always a pain when I want to get my phone ready for someone who can see... turning brightness up, Voiceover off, and then remembering to turn brightness down again.

I need to hand my phone to a sighted person relatively often for various reasons as well. I have the iPhone 15 Pro with the action button, so I use it to run this shortcut. I have it set to toggle voiceover and the screen brightness. I have the brightness going from 0 to 100, but you can change those levels to whatever you want. I think you can set a shortcut to a backtap too if you don't have an action button.
https://www.icloud.com/shortcuts/f8c5a7bdcb974b86a775c51d5eeba836

Thank you so much for sharing this, it's awesome!!!