Here's a few thoughts-
Selling knitting and crochet items is very difficult. People do t want to pay for the yarn or time you put in. Honestly the best suggestion I can offer is maybe a craft sale, holiday sale or even a yard sale and don't charge a lot. How much you charge is hard. If you charge too much they won't bother. So you try one price... Then lower it if no one is buying.
Personally I love making hats. I live in southern CA and we rarely need warm clothes. I experiment with color and design in them. Then I donate them.. I probably donate 99% of what I make to charity. Last year my husband took a bunch to the college where he takes a class and gave them to college kids. A few gave him about $5 which was nice, but not expected. What you make and what you do with it is up to you. We cannot tell you what to do because we are all different.
As for a blanket.. My preference would be to make flat panels. You can make strips and sew them together. Various multi color strips would be beautiful. I gave you YouTube links in an earlier post and one of the videos is for flat knitting on your machine.
I can't really help you more than this. No one here can.