Ha, that reminds me that I used Keynote to create an animated music video to accompany a ‘parody’ of All About the Bass I did for a lesson on stability.
I carefully got the timings of the transitions to match the beat, then made a Keynote with hundreds of slides. It needed some adjusting in FCP, but it worked.
Keynote is the designer’s Swiss army knife!
Some people – not me – use Logic Pro to edit podcasts.
This sounds like Glideapps. I used to build mobile apps with spreadsheet. Easy and beautiful.
How are you using Noteplan and Obsidian differently, now that you’re using both? Now that Obsidian has mobile apps in general availability, what do you get from Noteplan that you don’t get from Obsidian?
Doesn’t the Finder (on Mac) and Files (on iPhone/iPad) do the same? What value do you get form DT that you don’t get from the native OS filesystems?
I know you were not asking me but I’ll chime in for what’s worth. I use DT primarily for two functions:
Y’all mean “file conversion,” right?
I try to limit conversation with nonsentient beings to talking with pets and swearing at things I tripped over.
Oh man!! Of course, conversion. 
But sometimes talking to my apps is easier than some people I know! 
Obsidian doesn’t really feel native to me on either platform. I tend to use it for particular projects that benefit from it’s specific features (like using the dataview plugin to help organize my apartment search). For general linked notetaking I’m still using Noteplan.
Search in the Files app on iOS does not do full text search within documents, DEVONthink does.
On the Mac, I find that Spotlight (and even better, HoudaSpot) do a good job finding lots of documents that match search terms. However, DEVONthink does much better at sorting the stuff based on relevance. If I search for “safety”, Spotlight will get me every document that mentions safety. DEVONthink will put documents where safety is the primary topic at the top of the list, above those that just mention safety in passing.