My notes are #PlainText first, #Markdown second. They're highly portable between platforms, apps, and devices. #macos and #ios are my weapons of choice, but they'd look and work the same on #android and #Windows.
They aren't #Obsidian notes, or #Logseq / #iaWriter / #tangent / #TextEdit / #Nota / #AnyType / #Taio / #TaskPaper / #vsCode notes, though I can use any of those apps as a lens to view and work with them.
They're wild, and free. This is their theme song:
https://www.youtube.com/watch?v=iYFk_EsZ_D8