Zyrkon

This, 100%.

Moreover, the feeling on the iPad for writing is not good, and it needs a few upgrades (Paperlike screen protector, maybe Paperlike Apple Pencil grip, to make long-time use more comfortable) which is another $60 on top.

I bought a linked Notebook on Etsy, just to have a basic category system. I think it has 13 categories, and each Category has 20 pages by default, with links to each page. ~250 pages in total. And if you need to go massive, then you can use the sub-categories (single pages) as proper sub-categories, and add more pages after each sub-category, increasing the size indefinitely. Just that there are no links to the manually added pages, but that's what the categories are for.

And some nice book covers and such, to make the front page look nice.

If I wasn't using (and preferring) Obsidian as a knowledge-base-app, todo-list-app, and daily-journal-app, I'd probably also buy a calendar template. I'd most likely buy it from WHOLEHEARTED ME on Etsy, just because she also put in the effort to make over a hundred tutorial videos for reMarkable.

As to what other things I like to use the reMarkable for: Have you tried reading an e-book on it? It's surprisingly good. I'm pretty sure it can't do EPUB (not tested), but I'd say I prefer it over the iPad, just because it doesn't have any brightness. It's effortless on the eyes when reading a book for 3 to 4 hours.

Apple notes uses its rich text format, that is incompatible with everything else, including Markdown.

However, Apple Notes did get improved PDF support recently, did it not? And with reMarkable connect, you can connect the synching-feature to the iCloud drive and store all your handwritten notes as PDF. Once there, you can add them to Apple notes.

You can make a Shortcut that takes all new PDF files in a (iCloud drive) folder and creates a new note in Apple Notes for each new PDF file, then adds the PDF file to the note. Or take all the PDF files that you manually select, etc. (there are tutorials for Shortcuts on YouTube).

They are all sulking in the dark corners of the basement, I'd assume.

I've been filling out questionnaires for a while, and requesting autocorrecting lines. So I'm thrilled! :-D

Maybe we could get a digital ruler and angle triangle that we could digitally put on the paper and manipulate? :-)