I did a brief search and nobody seemed to discuss this.
Why carry a mirror?
To check on your appearance: e.g. see if there’s food stuck in your teeth. Also, I keep getting eyelashes in my eyes.
To peer around corners/behind things: e.g. plugging in a computer.
If you’re the outdoors type, you can use it to signal if you get lost.
I think most people will carry an acrylic one, which is light and unbreakable, but it scratches easily. You could get glass, but that breaks. I wanted a credit card sized one to put in my wallet, but there aren’t many choices for this, even on Amazon. I finally found a 304 stainless steel one from eBay. Yes! I thought it would be “indestructible”. Surprisingly, it got fine scratches after I ran my finger over it! So I stuck a screen protector on it. They seem to last long enough on my phone and I can easily replace it. You could also buy a mirror polished card holder.
The stainless steel one feels solid and a bit heavy, so I realised it can also function as a pry bar, if you don’t mind damaging the corners, and a scraper. Maybe I don’t have to carry a separate pry bar. How about a mirror/pry bar/nail puller/bottle opener/driver/box cutter with custom screen protectors to protect the mirror?
Lastly, I’d like to say inspecting mirrors is a job I can clearly see myself doing 