If you’re willing to do a little leg work, this can already be done with the help of an app like Tasker.
First you set up separate app styles for your Portrait/Landscape layouts. Then you set up a Tasker profile to trigger on screen rotation, which broadcasts an intent to Symfonium to switch App Styles.
It sounds more complicated than it really is. If you’re interested in doing it this way, I could probably share a Tasker “Profile” for you to import and use.