Two interesting options I haven't heard mentioned yet
1) Davis Mills. A good option? No, of course not, freak you. But he did produce in Houston with a slightly better o-line and substantially worse skill players. Houston doesn't give a freak about winning this season (Stroud's the future, Keenum's the mentor). Mills is also on an affordable rookie deal.
2) Malik Cunningham. I'd love to pluck someone from Belichick.