On my Xperia 10 III, the autofocus works, but it is rather slow. I can’t compare to the stock android version (I don’t have an android at hand), but as far as I remember, on android it was quite useful.
It works ok on Sailfish OS for static pictures in good light, everything else is rather pointless and, I would say, on the level of a 20 year old digital consumer camera.
This may improve once Camera2 API is implemented, but I can’t well if and when this will be the case.
If you have no autofocus at all (try it under good lighting condition on a high contract subject), then there is probably something broken. Did you test if the camera worked before you flashed Sailfish OS?