I have a packaged PWA as a Trusted Web Activity using bubblewrap for distribution to Google Play and the Galaxy Store. It registers as a share target for files from other apps. When the user’s default browser is set to Chrome (i.e. the TWA renders using Chrome), the app correctly receives any files shared to it.
However, if Samsung Internet is the default browser, files are not received. When debugging on v184.108.40.206, it just opens the homepage (start_url), and not the specific action URL defined for Share Target. There are no errors in the devtools console. The app does still appear in Android’s share sheet, though.
I should note that the Share Target API works correctly if the PWA/website is installed from the Samsung Internet installation prompt (like a WebAPK). This only affects TWAs.