In the UK, it's pretty normal to say "oh two twenty-three" for 0223 or "fourteen thirty-five" for 1435.

But when being less precise, we might say any of "half two this afternoon", "two thirty pm", or "fourteen thirty" depending on context.

As we do still use the 12 hour clock in less-formal situations, using an "oh" prefix for times before 1000 gives an extra point of disambiguation.

Interesting that you say the 'o' to explicitly indicate the 24h format.

In France we just say "let's meet tomorrow at 8 hours" for example, to which the person has to ask something like "Wait, do you mean at 8 hours or 20 hours?"

It's usually obvious from the context, but not always.