I’ve only just started the physical build for my mirror so just getting around to this stage (although not on your scale!).
If this is going to used by members of the public, then perhaps acrylic may be best? I’m thinking for safety and also weight reduction. If the build is going to be moved around or transported, the glass option will be seriously heavy (and fragile) at that size.
I’m a part time picture framer and work with glass sheets slightly larger than what you’ve specified and they’re seriously fragile at that size - bend and flex a surprising amount, quite scary. The weight is also quite surprising.