Every attribute is defined for every note; if you exported every attribute, you’d have a list of hundreds of attributes for each note.
What I think you want to do is export every key attribute for a note. You can do this, but I’m not sure it’s a great idea.
If you have one or more prototypes for each of the sorts of things you’re exporting, and each prototype has its own template, it’s really easy to export ^value($SomeAttribute) for each thing you want to export. If you want to export more stuff, or change the way its formatted, everything is in the template. If you use the same template for everything, changes are harder.
Still, this will do what you want. Spaces and line breaks added for clarity; take them out before trying this.
What we do here is build an HTML string piecewise in $MyString, and then export $MyString. It gets the job done, but if (for example) you wanted to switch to tabular markup, it’d be a bit of a nuisance.