If anyone finds they can't get the Google Street View URLS to work for them in the above add-ins (in their version of Pro, such as a pre 2.9 version), I wonder if a last-resort option could be:
Create an add-in that copies the lat/long to the clipboard. Then the user would paste the coordinates into the Google Maps search bar. That might still be better than looking up the address, etc. manually in Google Maps/Street View.