StorePilot could be possible to extend for users by creating WP plugins. StorePilot then needs to add integration support, with a plugin guide for how to build a StorePilot extension.
StorePilot could for example provide an api to add additional menu pages which returns data from wordpress in a webview, or additional payment methods / payment processors / shipping processors could be added instead of a main menu. Core StorePilot features (like open modals) could be possible through an API delivered by StorePilot.
Vue framework could be recommended, but not required to create an extension. Extensions could be possible to sell.