I knew how to read basic sheet music stuff from playing piano/taking piano lessons. Sight reading is hugely emphasized there. The stuff I learned on piano transferred over a little, but not actually that much because sheet music has quite a few weaknesses for guitar. I am not really that sure I think the way we learn by tab + ear is all that bad. I think you can go back to working on sight reading later after you have more fundamentals. My guitar teacher has certainly said there has been no real importance in emphasizing sight reading without tabs early on. He is quite good at it but didn't focus on it till he was studying for a music degrees. I think building your "internal metronome" is every bit as important as any of this other stuff.. time spent on sight reading vs single line melodies and all the other stuff is futile if your not playing a steady tempo... learning to strum in time is super important to build that internal sense of rhythm. This has been a big focus of my first 3 years of lessons. This was one of the biggest weaknesses when I was taking piano FWIW. Piano lessons with multiple teachers had a huge emphasis on sight reading + playing the melody + accompaniment at the same time that I ended up always being off with rhythm.. I could play the melody + accompaniment at the same time with "free rhythm/time" but as soon as the metronome came on I'd be a disaster. When you practice guitar we have much more of a learning system around just playing accompaniment/rhythm and learning to play that one part locked into the rhythm.. I think it's a huge positive about the way guitar gets taught.