Can I apply for OPT while my I485 is pending and I140 is approve

Dear people (Xiao Baitu or other high hands),
I applied NIW as a F1 student. My I140 was approved last July, but I485 is pending. Should I apply EAD card or OPT because I will graduate in August? I want to use OPT as a backup identity. But I am not sure whether I am still qualified since it is a non-immigration identity. BTW, does applying EAD now have any disadvantages?
Thank you very much!