According to the w3w API Docs you can submit a URL request with coordinates as parameters. However, I'm not certain that such a thing is possible in the context of an Arcade popup.
You can add w3w as a locator in AGOL, but I don't know that it's exactly what you're looking for.
Also, you have to take into consideration browser support.
I’m trying to start work with AGOL and this was very clarifying.
Mary Dailey | Borough of Manhattan Community College
paper writer service