Make Speak appear in the Share list

[KaiVinter]

It's me again!
There are some apps on which I would like to have text read, like eBoox. But it has its own way and UI to select text, and the usual Google menu doesn't appear. So I thought having Speak appear in the Share list would be useful, so I can share the selected text manually.

I found this, and it looks relevant:
https://stackoverflow.com/questions/11095122/how-to-make-my-android-app-appear-in-the-share-list-of-another-specific-app

Thanks!