As salamu alaykum, is your salah valid if you open something your 1 year old is asking and crying for you to open while you’re going in sujud or sitting in tashhud?

If it is for the well-being of the salah, so that you can concentrate—and they are being extremely loud and not letting you concentrate and have khushu—then yes, you can do so, and it does not affect your salah.