Sorry for the late reply. I hope you found the answer through other means by now, but in case not, virtually anything is possible through programming. This includes a dynamic menu like you describe. It’s a matter of querying for pages which all have a particular attribute like custom field or taxonomy term and outputting the returned pages in a manner compatible with what is expected for menus.
I’ve not used this plugin, but “JC Submenu” looks pretty close to what you are looking for. If not quite right, it could likely be adapted to fit with some custom coding.