Announce time in 12 hour format with 24 hour clock

Hello,

macOS will announce time as "It's six o'clock" etc with the 12-hour clock set but when the 24-hour clock is set it will say "It's eighteen hours" instead.

I prefer having the 24-hour clock on screen but I'd definitely prefer macOS to say "o'clock" as well.

Is there a way to get macOS to announce the time in the 12-hour format with the 24-hour clock on screen set?

I have already tried changing the time format in language and region, it doesn't seem to make a difference. The voice only changes when I select "use a 24-hour clock" in date & time settings.

Thank you.