I have weeds everywhere. If I had room for chickens i’d just harvest all the vegetables, let them roam over thhe renai if weeds and grass for a few weeks, enrich the soil and then put them elsewhere. I’d then plant seedlings in the now-weed-free soil.
My chickens say "Who wants to eat weeds? We like clover and grass!" and they walk around the weeds.
They are not hungry birds. I'd hate to let them get so hungry they will eat weeds they don't like.