How to Allow App to Open File in Public Share

I love that with the text editor, collabora and onlyoffice you can create a public share and the people with the link can open and edit the document in their browser even if they are not authenticated into nextcloud. I am using the really nice ownpad extension that embeds Etherpad into Nextcloud. It’s one limitation is that when you do a public share it offers only to download the .pad file and doesn’t do what the others do and allow for the person with the public link to edit in Nextcloud.

How did those other apps accomplish this? Is there a way to create a public link for another app like owncloud that will open the app for a non-authenticated user with a public link?