They have been approved through the FDA for emergency use, just as the Pfizer was. The Pfizer was the first emergency use approval hence why it will be the first true approval. The others will follow suit shortly after I’m sure.
That's not how approval works, all 3 vaccines have emergency use authorization. FDA approval was just an eventuality at this point the vaccines are safe with or without approval (as the 3 phases of clinical trials were already occurring for the EUA)