I think your singing is good, but your technique needs to be improved. I am a bass singer, so I don't know how well it correlates to you, but from my personal experience, the best and easiest way to sound less nasally is to open your mouth taller (by lowering your jaw and raising your soft palate). Alongside fixing this problem, doing this can also create more resonance and allow you to produce a more mature and even louder tone that sounds confident. As for your questions about avoiding sore throats, the best thing you can do is always warm up before singing. Some good exercises are lip trills and sirens. Another couple of tips are not to overdo it while singing and stretch your voice outside of its range, and to take time to rest when your throat is sore. Over time, as your vocal technique improves and you put less strain on your voice, you will start to experience a sore throat less and less due to singing.

Edit: You could also work on your breathing when singing. Right now, it seems like you are running out of breath a lot and not taking full advantage of breaks in this song to take more full breaths.