Would it be possible to add a “download” option to the hyperlink pop-up in writer? This allows direct generation of <a href=x" Download="x.pdf">link trigger</a>. This could also impact link in generated text document so it might also require other options, such as open in a separate window as in <a href="x" target="_blank">link trigger</a> and if both options are used, <a href="x" Download="x.pdf" target="_blank">link trigger</a> then as an HTML export Download is used and as a .odx document, target is used, or perhaps some other appropriate interpretation.
Note: edited by ajlittoz to remove a formatting typo