GrapheneOS
Pixel 8
Obtainium 1.1.55

As described in this closed issue, Free42 was working:

App Source URL: https://thomasokken.com/free42
Override source: HTML
Apply Version string extraction Regex to entire page: (on)
Version string extraction regexp: The latest release is .*?([\w.]+)<\/b>( for \D*Android|\.| for all other platforms\.)
Match group to use for version string extraction RegEx: $1

Note that there is only a single .apk link on that page, which is download/Free42Android.apk, and that never changes.

The version string is being extracted correctly; but this setup now produces the error, "Not Found". If I use the App Source URL https://thomasokken.com/free42/download, on the other hand, it works (but the version never changes).

• See here, where that complicated Version string extraction regexp is needed.