I can transfer money from Europe to Brazil in seconds with Wise. I press the button and the money is nearly instantly available in the Brazilian account via PIX. The same in the reverse direction is possible but only if you have a more modern bank in Europe, eg. N26 or Revolut.

I was thinking more of gp's comment "and the first user is an Argentinian bike importer that finds transacting with their suppliers to be challenging"

Wise isn't great for paying suppliers. Their business account limit for debit/credit is $2k, and for ACH is $50k. They have higher limits if you fund with wire, but then we're back at the starting problem again...

And still, you have no way of knowing that the receiving party actually got it. On a blockchain, the source-of-truth "database" is public.

My understanding is that Wise isn't a true international transfer. Wise has money already in a Brazilian account, and when they receive money in their European account then they send you money from their Brazilian account. If they don't have enough money in that Brazilian account then it can't be instant like it is today.

Not the full picture: Wise is that big that it has already lots of local accounts and/or correspondent banks; so basicly "you get the money from Wise" but from a "local payment way/scheme" (to which Wise is connected in the background through several layers)