Good job, on Pinephone needed to sudo apt-get install libqt5widgets5 and sudo apt-get install libqt5multimedia5 first.
For the record ran your Rockbox utility build for ARM64 with Mobian, works ok, just needed to set display to 100% to get it to fit on the screen.
SDL(200) Rockbox build itself also works unaltered on the Pinephone, would be nice to install it direct from the utility.