Turns out asking itself helped me get to the answer via another forum post!
This formula in the Tags property does it:
{{slice(split(51.body.path_lower; “/”); 2; -1)}}
I was using ChatGPT to help me do this but it was wrong on it’s belief that the Tags property needed a key:value style array when updated via the Notion Module…
The above just splits it more simply and it works - another bonus that it doesn’t require any additional operations!