I have come across new app in the making - KeyPoints - “an upcoming note-taking and PDF highlighting”. In Keypoints, notes are displayed next to the PDF:
Info here: https://keypoints.app/blog/
As I rarely use annotations, I don’t know whether DT does something similar already but if not then why not? 
Thanks for the link! This app seems to be “upcoming” actually now for almost 2 years 
Easier said than done?
(Marketing easier than coding?)
Probably. That’s one of the reasons why we rarely announce upcoming things.
Keypoint looks and smells a lot like Highlights (though I don’t know if that’s in development any longer).
Yes the dude still developing but there was a period it went by with no updates for more than a year.
Highlights is a side project according to the developer.
Hi, I’m the Keypoints developer. The app is in continuous development but since this is very much a part-time effort progress is pretty slow. The public website is just there so that I have something to point people to in case they are interested, and to gather initial feedback on the app’s intended workflow. For more info on the app’s current development status, see the Keypoints forums.
The basic idea behind Keypoints is indeed kinda similar to Highlights app. However, there are a few major differences: Keypoints stores & presents all of its highlight notes as individual plaintext notes so they are independent from each other and can be filtered/gathered freely. All note elements (like labels, keywords or links to other notes/files/publications) are hot-linked/clickable and can be used to form a network of notes (which can also be visualised). These note elements can be also set via the UI or scripting, and the note text will get updated accordingly.
Since both, DEVONthink and Keypoints, are heavily scriptable, I plan to deeply integrate it with DEVONthink so that notes, PDFs & metadata can be exchanged both ways. Scripting would likely also allow for a two-way sync of data.
Welcome @msteffens!
Since both, DEVONthink and Keypoints, are heavily scriptable,
Awesome!
plan to deeply integrate it with DEVONthink so that notes, PDFs & metadata can be exchanged both ways. Scripting would likely also allow for a two-way sync of data.
Even more awesome!
PS: I hope my comment didn’t come off rudely. We generally try to keep a light, friendly tone in here. 
PPS: Looking at the the app a litte more closely… you’ve got some great features in this app! Super impressed with the screencast you uploaded for the August 2019 update post. Keep up the good work!
PPPS: Are you using Apple’s PDFKit or something else?
@BLUEFROG, many thanks for the welcome and the motivating feedback!
The app indeed just uses Apple’s PDFKit framework.
Ahh… We do as well. Imperfect as it is, but generally works well enough.
Is the app available as an alpha or beta yet? I just subbed for notifications from you.
Thanks, @BLUEFROG. Unfortunately, the app isn’t yet available as an alpha or beta release. But I’ll let everyone on the mailing list know as soon as it is. And if I may, I’d also like to directly ask you for feedback at some point (to further discuss a possible integration between the apps).
Absolutely - though I’m sure we’d need the input from our CTO/Lead Developer too. But it’s always good to discuss healthy inter-application communications 