I don't think English/ Australian "Oy!" has anything to do with Yiddish "Oi!"

I don't either. Was making a segue!

So ladies don't say "Yo"?

*Canadian* ladies! Kidding around. Though, come to think of it, there may be a gendered aspect of it.

Have Brits started using "yo" at the end of sentences yet? I began noticing it about a dozen years ago.

This is along the lines of what I was also wondering - but was afraid to ask for fear it would lead to a confusing Internet back-and-forth. i.e.: if Britons are using "yo" like in America, or if the word exists in more limited use.
In "my" use, Yo is:
To get attention, in quieter setting: "Yo Michael!"
To get attention, when loud voice is needed: [someone far away has just dropped his wallet without noticing] "Yo!!!"
Greeting: "yo, what's up?"
To halt an action in progress: "yo yo yo"
Answering when one's name is called.
Reaction to a slight: [a car runs over my foot, or, someone cuts in line/queue] "yo...wtf?!"
Sustain someone's attention (?), at the end of sentence: "Don't be trying to bother me 'cause I gotta lotta work to do yo."

I realize most of that is the same as "hey," and not very remarkable! But it would be interesting (to me) if people in UK had adopted *all* the uses.

I don't (often) listen to Rap, so my primary association is not as a Rap-based "slang", but rather just an American word. Is it used consciously with "American" connotation, in UK?