Just stumbled upon this post of yours: Canvas limitations?
It’s pretty old and thus closed, but if you’re still looking for the solution – here it is:
Open the detail view of your canvas field
Select the kebab menu in the top right corner
Select Print & PDF → Export to PDF
You even get the option to export all rows displayed. So you can leverage filters/views to export multiple specific items in one go such as all meeting notes of last week for instance.
As far as I know there is still no way to trigger this via a formula. If it was, you could even export all meeting notes with the push of a canvas button … which is very close to the top of my wishlist.