A bizarre incident involving a mentally ill woman recently occurred at a store in Geoje, South Gyeongsang Province, where the suspect, wielding knives and wearing a cat mask, threatened employees and customers, including small children.
When the police arrested her and asked why she did it, she answered “meow” and said, “Can’t tell you that, meow.”
I suppose all the examples you give convey some little trace of the accent from their respective regions. Slightly longer final syllables in the UK for instance.
But more to the point, the spelling ‘miaow’ is completely new to me. But I receive very few letters from British cats so maybe that explains it.
Here’s an example from the BBC:
https://www.youtube.com/watch?v=qeUM1WDoOGY
Though just to mix things up, the BBC Earth YouTube channel appears to be using title case capitalization in that title, which is typically an American English style, there. The main BBC YouTube channel appears to use the more-usually British English sentence case capitalization.
So I expect that there’s always the possibility that people aren’t always super-religious about the form of English that they use.