Gather parameter from across shortcodes in page

I’m working on a staff listing page for a Hugo site that makes use of a custom shortcode that lets us tag each staff member with multiple subjects, which we then order and display separately in a list next to their entry:

John Doe
Senior Engineer
{{ expertise subjects="oracle, bananas, mangos, databases" }}

Jane Doe
{{ expertise subjects="mangos, file-cabinets, forms" }}

The shortcode works great, as expected, for each staff entry. But I am wondering if another bit of Hugo templating might be able to aggregate ALL subjects from all 25 shortcode entries in our page? I am imagining a list at the top or on the side of the subjects our staff has knowledge of:

bananas, databases, file-cabinets, forms, mangos, oracle

Or am I asking too much of shortcodes here? I realize I could create separate pages/metadata (one for each staffer) and then display all this in a list page. But I’d rather not have individual staff pages for such minimal content.

Shortcodes are rendered in order, so you could store values using Stash and access from the template.

I meant Scratch. Early morning in Norway. But as the content is lazily renderes you need to call one of the content methods first