9 Notes is a name I remember from a while back, even though I don't think AAWP has ever covered it before, other than listing it in directories. It's a note taker, but 90% graphical, with export to various other formats. And now it's been renamed to Paperly UWP, so I thought it worth highlighting.

From the Store description (which still refers to the old name):

Make notes with images, icons and drawings with the hand or stylus pen, 9 Notes helps combining words with images and icons to communicate your ideas, whether you're a content creator, journalist, blogger, researcher or student

• Windows Ink - Make drawings or handwriting writing with stylus pen
• Add images - Give life to your content by adding images, with options to edit and apply filters
• Text with formatting - You choose the best format for your text, alignment, font style, font family and weight
• Export - Export your content for editing in another device
• Make Transparent PNG - Craft pictures and icon with transparent background 
• Insert PDF files - Insert pages of a pdf file as an image in your whiteboard
• Easy whiteboard manipulation - Perfect for photo montage with 3 diferent filters to enhance your pictures

I tried to create some masterpiece plans for the sake of screenshotting, but utterly failed - plus the dialog to cancel out of quitting back a level is confusing and I (ahem) lost everything. So here are some of the promo graphics, to give you an idea as to overall functionality:

A typical structure would be a number of notebooks, each with a number of pages in it, building up relevant material and getting ideas down. Me, I'm more of a wordsmith....! Here a sketch has been added to a Paperly page...

You can insert/embed photos and other relevant images too, though you'd need the Pro version and high resolution pages, otherwise everything would seem too low-res. There's clearly an element of desktop publishing going on here, though it would obviously work better on a much larger screen, for example on a Surface Pro or other Windows 10 device.

I get it, graphics, text styles, and so on. But would you really develop invites, brochures, etc. using a 5.2" phone screen? Really?

You can grab Paperly UWP here in the Store. 'Pro' features are an in-app purchase away (higher resolution, more export options, etc.) I'm still not sure about such graphical idea-taking tools on mobile - and you can 'Save as' here or export to generic formats, but I'd have thought a cloud-synced system whereby your content was available on all Microsoft-signed-in devices made more sense.