My zettelkasten is digital and based on Drafts. I call it zettelkasten though the technique is quite different (the lack of slips is not the only difference) because the aim and process are the same.
Instead of analog zettels, I have digital ones (each one is a draft), respecting the zettelkasten principles, incl. unicity of zettelkasten (for life and work purposes), atomicity and autonomy of notes, and links everywhere.
The notes are linked together and connected to outside documents (links to web sites or Apple Notes with scanned paper documents for instance ; or references to books and articles).
The Drafts app and its multiple actions allow to search notes with keywords and navigate easily between drafts and also to refered documents. And notes are created nearly as fast as the thinking process.
I chose the Drafts app for these reasons, and also because it perfectly integrates with my diary system (which also is linked to zettelkasten notes). One app and multiple uses for one common tool : text !