Someone mentioned Ireland upthread. I love the habit among some Irish speakers of putting 'so' at the end of a sentence but hadn't noticed a specifically Irish usage of 'so' at the beginning of a sentence? Is it in fact just the same usage that has also become popular in the UK?
Like in the UK, the annoying 'so' as a filler, in response to a question, and typically in radio / TV interviews, has become common.
However, this is known as a 'discourse maker' and covered here: dictionary.cambridge.org/grammar/british-grammar/so
There are many others eg 'y'know' or 'look' or 'well'. They vary with time & region but function as a marker for 'I'm about to say something requiring attention'.
The traditional Irish 'so', as others have said, is much more used, at the end of sentences:
'I did, so I did'
'Sure I will, so'
(Having been through a Schitt's Creek binge, once again, I now horrifyingly find myself using all David & Alexis's discourse makers, unintentionally, including the dreaded 'I mean...' 😮💨)