I have not tried Wero, but I have tried the german predecessor (paydirekt/giropay). It was ... not much less smooth than PayPal.
But I’ve only ever seen a single vendor offering it. 0 for Wero so far.
I don't think vendors can offer Wero yet. I think it's part of the merger with other European companies.
In most countries, Wero is still in incubating stage. i.e., banks anouncing that in the next 3 years they will support it.
Of course it's not widely used by vendors when it's still in development. I am hopeful that it will take off to some degree in the nearest 5 years though.