If I have greencard and I had to stay out of USA...

We would like to inform you that it is known that being 6 months out USA is a reason to lose the residence. However, due to Corona situation and closing the ports to stop the virus spreading which is strong matter out of control, then you may not have any problem if you are out for more than the legal period.
We advise you to review the USA Embassy to arrange the travel matters as soon as possible to avoid losing the residence.