Contributed by Matthias "Ba" Prögel 🇩🇪
Matthias took the SPI display refresh rate issue seriously and decided to use an HDMI screen instead, which completely solves the framerate issue and even spares you the hassle of creating the messy display cable.
The display he used is the Waveshare 3,5 inch Raspberry Pi Resistive Touchscreen HDMI LCD Display 480x320 IPS, and here's a perfect Flat, short and flexible HDMI cable for the job.
You can see here how Matthias got the HDMI working: He's taking power from the Raspberry pins with some cables, and a short and flexible HDMI replaces the messy SPI cable. He also added some rad mods to include a volume control.
Download the 3D STL files Matthias has modified to fit this HDMI display in the Commodore PET Mini files repository, under the Other files directory.