There are various portfolio and CV management systems out there, some of which have integration with Moodle, e.g. Mahara: https://mahara.org//
One issue with such systems is one of ownership and personal investment, i.e. Why would learners want to spend the time on creating an online CV/portfolio on your system? Who has ownership of it? If the learner leaves and goes to another organisation, can they take it with them? Will it be compatible with other CV/portfolio systems?
I'm looking into using Wordpress to create blog networks so that learners can be given their own blogs on which to manage their portfolios/CVs. A lot of individuals use blogs in this way already and I think it's easier to learn to use, more flexible and has better support for multimedia and file management than any of the CV/portfolio systems I've seen. Wordpress also has plugins for password protecting pages and posts to limit/restrict access. You'd simply be providing a service and some rudimentary technical support while they get started and when they're ready, they can export their blogs to their own Wordpress, e.g. on their own hosting provider or on Wordpress.com.