Have you tried [GoodTask3]( http://goodtaskapp.com/ )? It's effectively a task management app that uses Reminders as its database. I was previously a Todoist diehard, but wanted to stay more within the Apple ecosystem (for security reasons, for the purposes of using Siri more effectively, because I'm already paying for iCloud). GoodTask is really cool and it gives you a lot more features than what you have in Reminders. Also highly customizable.
I know of an active Reminders transparency layer. I use Good Task, that works directly with Reminders offering easier management, smart folders, tagging, etc. Many apps offer these, but then you sync to their cloud, etc. What I like about Good Task is that it natively works with Apple Reminders. And you can completely drop Good Task in the future and have your reminders stay behind. They have their own forum.
This is one of the big reasons I recently moved from Things3 to Apple Reminders. I need to be able to share tasks with my spouse and I didn't want to have my to-dos spread out across multiple apps. Things3 is great from a UI perspective, but I personally just needed more functionality. I've also found location-based reminders to be incredibly helpful. I use them all the time now.
I love using Reminders in conjunction with GoodTask. I use both apps together, sometimes going into Reminders and sometimes going into GoodTask. GoodTask brings some more features to Reminders, but it's implemented in such a way that you don't have to exclusively use the app. I set up GoodTask to look and work a bit like Things and it's working really well for me.
In not so many words an app is native to a platform if it was built specifically for that platform. The source code for apps that run on macOS is only available if the developers make it open source on GitHub or the like. You could then take the source code, make any changes you want and then compile the whole app yourself.
While that may not be an option for many of the popular task managers, there are some options that act simply as an interface for other apps. GoodTask and 2Do can both do this with Reminders.
This won’t be helpful, but that’s the exact reason I switched to GoodTask 3. It’s built on Reminders, but has all the flexibility of the more advanced apps. I just got sick of having to remember to be so specific about the wording with Siri.
I'm not sure this is possible.
The app supports the <em>x-callback-url</em> protocol, and I'm able to open a list of reminders, but it doesn't perform the call back when given a URL scheme for the shortcut to return that data.
You mention there doesn't seem to be an easy way to parse the data, have you managed to get back any programatic data at all?
As far as Reminders is concerned I've found that using http://goodtaskapp.com bridges a lot of the gaps between the two . As it uses Reminders as it's back-end you don't lose anything from trying it out and it takes advantage of all the good things Reminders has to offer .
Last week The Sweet Setup posted a comparison review for iOS and they ended up recommending the free, built-in Reminders app.
One app they did not mention, which I use, is GoodTask, which is a superset of the Reminders app, accesses the data from Reminders and syncs with it (and with data from Calendars), and works with Siri. The app is free but you can unlock 'pro' features ( 'Bulk Actions', unlimited 'Quick Actions', unlimited 'Add Presets & Text Snippets', various preferences options, settings for Widget & Watch) via in-app purchase. (I did not upgrade.) There's also a syncable Mac app.