ls says about 6.4MB for the full firmware image, comprising 2M for the kernel (hmm, not sure why that’s grown so large, it was 1.4MB or so last time I was paying attention) and the rest for the compressed root fs. It’s already using musl: I was pleasantly surprised (bordering on stunned) to find how easy it was to switch.
[dan@loaclhost:/srv/media]$ ls -lh /tftp/
-r--r--r-- 1 dan users 6.4M Jan 1 1970 firmware.bin
-r--r--r-- 1 dan users 2.0M Jan 1 1970 kernel.image
-r--r--r-- 1 dan users 4.3M Jan 1 1970 rootfs.image
firmware.bin is the image you can actually flash: the separate kernel/rootfs files are development versions that can run entirely from RAM (if you have enough of it)