I didn’t understand why you are creating multiple topics on same issue as already i have given you the working method of bookmark function.
If you spam on community for help, no one will help you.
One more time I am posting my solution here, take a look on it and make necessary changes according to your app.
First block is for viewing saved bookmarks.
And second for adding new bookmark.
I have used two floating buttons for these functions, in your case you have to use :
Second blocks on extra button clicked.
In place of “list view selection” set value which you want to save as bookmark. In your case, if you want to save list items on extra button clicked then use title or element index in place of “list View selection”
One more list view os required to show saved bookmarks in a list as you see in first block, i have used 2 list views.