Apple Notes could be a good tool for the Zettelkasten method. It syncs fast, has great search and works across all Apple devices nicely.
It's also got a nice UI. You can even take voice notes with Siri. It's not ideal for the Zettelkasten method, though as it:
1. Doesn't support Markdown. Essential for publishing. I hate writing in rich text
2. Has no internal links. That's a real-time saver and critical to the method
3. Exporting notes from Apple Notes to another writing app is painful and introduces formatting errors.
I use Apple Notes for short-form notes and then transfer the results to the Zettelkasten.
My current app of choice for the Zettelkasten is @obsdmd I also like the Archive
I use Ulysses for turning longer Zettel notes into articles