Added: Anyone with the link in a document's Share drawer. Turn it on and the drawer shows the document's link to copy. Anyone who opens it can read the document without signing in, on a page that shows its text, pictures, tables and notes, without comments, suggestions or editing controls. Readers can switch between Flow, one continuous column, and Pages, pages the shape of the document's paper.
On a paid plan, type one or more email addresses under the link, add a note if you want, and select Send link. The email has a Read document button, replies go to your own address, and you get an email when someone opens the link.
Turning the switch off stops the link opening the document. Turning it on again brings back the same link.