Often the pdf documents have ~1" margins and there have been paragraphs that I would either like to add my own commentary, create a small sketch of an idea, or note an idea related to the material. The margins aren't big enough to fit, but adding a whole blank notes page is too large (I use an iPad Pro).

I request a feature for having a color indicated "sticky note" that fits on either side of the margins and can be placed anywhere alongside it. Tap the little box, and the expanded note comes into view with various options for text, changing note color etc...

Truth be told, the text zoom feature interface that is already in place would work fantastic for this sticky notes feature.

Great App!!!
I use the Zoom Windows to write notes. I encode items like reminders and events with title, date time, list name, and people using delimiters such as '#today$Buy some milk€Shopping' for a reminder or '$Risk meeting for ProjectX#23/7/18t12h30-13h00@Me;Email.address@domain.com' for an event. I then select the writing using the Lasso Tool to convert to text. I then share this text with Workflow extensions I have created which parses the examples into a reminder or event etc. It works great ;-)
A long-shot... but... Could you create a button which lassos the area between the top and bottom of the page and the left and right margins (I also use the margins for other purposes) and convert this. I would then send this area to a Workflow to parse the whole page. Cheers, M.