FWIW, as a hiring manager although I’d like to help people - I would be hesitant to ask for any feedback beyond the actual interview session. There are public and private reasons why you won’t get hired. I haven’t hired people simply because they come off as unenthusiastic and shitty people even though there work is great.
The portfolio is weak, but lack of experience could also show a lack of knowledge about manufacturing, 3D tools, technology, etc - or have just been their nice way of sugar coating the no. Similar to the “not a good fit” messaging which is so often used.
The feedback that was given here, especially your clear comments on how projects are coming across for a new grad are far more valuable than anything you would ever get out of a hiring manager or interviewee, because you have an active goal in trying to be helpful - a hiring manager will not.