Apple Notes used to allow single export in PDF and plain text (iPhone and iPad) while multiple notes export can be done by drag and drop files to Files app but rtfd format only, and requesting copies through Apple’s website which needs to wait on Mac only.
I used to know the latest markdown export can be done on individual notes only until reading the following article and testing it on my iPad that bulk Markdown export with attachments is also possible, and not limited to desktop now.
I have no idea how to work on iPhone, but I think it’s not available. I am not sure if it works on Mac as mine can’t be updated to macOS 26, but Exporter app is good enough for me when I need.