On Beryl, firmware 3.216, any form of WPA3 does not appear to work with iPhone.
This is a known issue, discussed at Beryl WPA3 Issue with iPhone
On my Slate AX running firmware 4.20, WPA3 (and all variants) works fine.
On my Beryl AX, firmware 4.21,
For the 5GHz band, WPA2/WPA3 mixed mode works fine for both M1 mac and iOS 16+. WPA3 only also works for both.
For the 2.4GHz band, WPA2/WP3 mixed mode works fine for M1 mac. M1 mac confirms WPA3 connection.
For iOS, WPA2/WPA3 mixed mode does not connect on 2.4 GHz.
For iOS, WPA3 only mode works for 2.4 GHz.
Summary:
For the Beryl AX running firmware 4.21, it appears that WPA2/WPA3 mixed mode on the 2.4GHz band appears to cause compatibility problems with iPhone.