Building Tenant Sass

We have a multi-tenant application where each tenant has their own Git repository for their theme. Tenants use our service and want the displayed site to match their main websites. We use Mustache to make sure the tenants can't run any code in their views - they can only change the way existing data is displayed. When a tenant makes changes to their theme - either through a simple editor, directly to the Git repository, or using a program we provide that scrapes a selected page on their main website - it is automatically loaded on our webservers. Anytime a tenant loads a view, we search through the views for the selected tenant and our default fallback views for the first match. This gives our tenants a simple way to customize their display.

We now want to allow each tenant to supply their own SCSS. Is there a way to have our main webpack configuration either loop through the tenants and process their SCSS?