I needed to switch from the internal eMMC card in the Allo USBridge to an SD, so I got the latest OS image for Sparky (DietPi_SparkySBC-ARMv7-Bullseye) from their download page, but it was only 815 MB in size and did not give me a working Roon endpoint despite efforts to reinstall via config.
I then found an earlier version elsewhere which contained a 2.15 GB image that performed as expected: http://3.230.113.73:9011/Allocom/SparkyUSBridge/DietPi_SparkySBC-ARMv7-Bullseye_AlloGUI.img.zip