What, exactly, do you mean by, "supports" ?
Sure, it's capable of running Zephyr.
Do you mean the question the other way round; ie, "What support does Zephyr provide for the STM32H723VGT6?"
In what way(s) does @LCE's previous reply not answer your question?
Did you see the Supported Features section at the bottom of the linked page:
https://docs.zephyrproject.org/latest/boards/st/nucleo_h723zg/doc/index.html#supported-features
Zephyr community has a Discord channel amd Developer Mailing List.
A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.
