Solution:
This is technically possible, but it’s not something that will work out of the box. Your custom frontend will have to ‘understand’ the content Visual Composer produces, thus VC has to be loaded in the frontend as well.
On a data level VC populates the post with custom shortcodes and ‘deciphers’ them in the frontend. Start with VC Wiki: https://wpbakery.atlassian.net/wiki/display/VC/Visual+Composer+Pagebuilder+for+WordPress and specifically API section: https://wpbakery.atlassian.net/wiki/display/VC/Inner+API