Please see readme-sailfish.

This uses the Qt5.15 meta packages, and needs an app called qt-runner for launching the apps in a separate wayland client, providing also the SailfishOS keyboard.

So, it's not 'native' in the look & feel sense (no Sailfish specific QML items available), but allows basically any Qt5.15 compiled app to run on SailfishOS, which is great news!

Obligatory screenshot: cl-repl-sailfish