Can you get like a open work visa and do freelace .
Sorry, I am afraid that you can't. In order to apply for a Z type, you need to find an employer first. Your employer can help you acquire the work permit. Then you can use the work permit to apply for the Z type. So you may not apply for the Z type successfully if you just plan to do frelance.
However, you may do some freelance work after you get the Z type. You'd better not let your employer know about this.