Glad to hear that the pipe was actually available separately.
I have a question, now that the the new pipe arrived.
Is it threaded, or is it just pushed in?
I would try to resist the temptation to cut it shorter, as you’ll have that much less to work with.
Keep blasting penetrant into the joint between the pipe and manifold. After each blast, let that stuff seep in for a few minutes before getting back to it.
Which pliers did you wind up using, if I may ask?
Whenever you do get it out, I would clean the hole very well, in preparation for the new pipe.
And when you do get the new pipe installed, make sure it doesn’t have any nicks or burrs from the installation process. You wouldn’t want to damage the hose.