ThreadReaderApp Shortcut

Here’s a quick solution using the Tweet action from Aviary, but you could substitute any client with Shortcuts actions.

ThreadReaderAppShortcutScreenshot
ThreadReaderAppShortcutScreenshot

It makes use of the first of the two methods to “unroll” threads listed in the app’s help page and just Tweets @threadreaderapp unroll [Tweet URL]. I also set it to appear in the share sheet.