Students may be able to download their e-portfolio, but what does a cadet do with their file on a thumb-drive? Is there a platform that they can upload it to so that they can manage it themselves (without Canvas)?
So when you download the zip file of your eportfolio you get two things
So yes, a student could take the files and theoretically host them somewhere else, but it would take a bit of know how on the students end.
If a student just wants to grab files from past submissions, they can alternatively: Sign-in to Canvas > click their profile picture (account) > click files > click "My Files" > click "Submissions". Here they can see past submissions they made to courses and download any of them.
To support what Chofer said, Portfolium looks like a nicer version of eportfolio. eportfolio is clunky, slow to use, and as you can see kind of difficult to host outside of Canvas. Portfolium seems like it has some really neat features (and I would imagine) it's probably a bit nicer to use. I hope this helps answer your question.
Do you know if your school has explored Portfolium? This is a partnership that was announced a few years ago at an InstructureCon conference. As I understand it, it's a free integration with Canvas. It has a lot more features than what Canvas ePortfolios have to offer. You might want to have a conversation with your school's local Canvas administrator or someone from your school's Online Learning/eLearning department. They may be able to have a conversation with your school's assigned Customer Success Manager (CSM) at Instructure about getting it enabled at your school. You might want to check out these resources, too:
I hope this will help a bit. Sing out if you have any other question about this...thanks! Be well...