Advanced share
An outside person can comment and accept or reject what you shared.
What it is
Advanced share is a review, not only a viewing link. The outside person can leave a comment and send an explicit accept or reject. The thread stays on that link.
Where to find it
From the case, when the feature is on. The public page is the link you send. Admins still see the link in Shared.
How it works
Share the case the same way you would send a viewing link, with advanced share turned on for that share. The reviewer responds on the page. You read the decision and the comments without giving them an account.
Good to know
Advanced share is on every plan. The owner turns it on or off under Billing. A plain share link is the right tool when nobody has to answer.