I was caught out at the office the other day when I wanted to listen to a podcast on my lunchtime walk but forgot my AirPods.
Instead, I turned the speaker volume right down to barely audible then held my iPhone upside down to my ear like a traditional phone where the speaker is positioned. Amazingly, it was perfectly clear and not disturbing others with my noise.
The only problem was having to walk around with my arm up for 20 mins but this used to be the norm.