Hi,
To be honest – it is probably first time when I see such request, so at this moment we have no plans for it 🙂
Also it can be quite tricky to implement for the all languages.
I think that you should consider your own implementation using custom theme helpers: https://getpublii.com/dev/how-to-create-custom-handlebars-helpers/ as an argument you can put your post content and then do necessary calculations.