I taught my daughter to read when she was 4 and she was reading ~30 page books in kindergarten. Nothing outrageous, but she was pretty far ahead of her class that were still going over ABCs. This was outside of a few other kids who had parents that also taught them to read that were more or less on the same level as her. I didn't bother trying to teach every last freaking phonics rule, I just taught her the different sounds each letter could make and started doing some 2 or 3 letter words each night where we'd sound out different options if the first attempt didn't work. Eventually we talked about "at" versus "ate" and when it mostly made sense to use short and long sounds. I had to relearn some of this myself while going through it. I had to warn her about weird cases a lot, but she caught on super quick. The whole idea though was to get her into those basic 5 page books and then incrementally up the difficulty rather than memorize a thousand rules up front like some poor student taking latin. Phonics is absolutely essential, but I fear that schools go overboard with it.