I’ve always been a fan of radio drama, (having grown up with the radio version of Children’s Hour, etc), so I’d been hoping to eventually find some on Radio Cymru, and (although I’ve missed episode 1) now there is some:
The 2nd, and current episode:
“Llwch yn yr Haul”, apparently based on a novel:
by Marlyn Samuel
The dialogue is nice and clear, appears to be mostly gog Welsh, and doesn’t sound too difficult to understand.