Yes heck sausages can be cooked from frozen.
All types of sausages including heck sausage can be cooked from frozen without thawing them out first.
Just know that when cooking frozen sausages that it will take around a few minutes longer to fully cook and it can be hard to know if the inside of the sausage is fully cooked.
That's because the outside of the sausage may cook faster while the inside of the sausage can still be partially raw.
So you must ensure the inside of the sausage is cooked all the way through as well.
I prefer to thaw my sausages out in the refrigerator overnight before cooking them because the sausages cook faster and more evenly when thawed out.