I’ve been making progress on a modification of the library for Teensy 4.0 / 4.1. It runs fine at 256x128 with RGB888 color and also supports decreased color depth with increased framerate. I’m hoping to release a new library branch in the next couple weeks. I have not tested SD card access, but I’m planning to do so once I get my hands on a Teensy 4.1.
Currently this requires some hardware modification of the SmartLED shield V4 but nothing too difficult. That situation may also change soon…