How to attach a bamboo type shade to ductwork?

why not just hang the shade infront the the ducts

dont attatch to duct work, attatch to the rafters.use a staple gun with longer staples.

If you don’t need to actually roll it up and down, you can just cut off the mechanism And attach it to the ceiling With an appropriate length 1” x 3” wood strip to keep it firm.

Or attach a 2” x 4”, painted to make it unobtrusive and hang the shade by brackets that fit to that “beam” And the brackets.

Use gorilla glue. Just make sure it doesn't seep through into the duct.

You could use thin jute rope to attach (tie) the shade to the rafters. Don't attach anything to the ductwork as that could cause a fire.

Lowes has "Anchor Wire Gorilla Hooks" that are the easiest way to hang just about anything...

https://www.lowes.com/pd/Anchor-Wire-Gorilla-Hook-Picture-Hanger/3084923

Just an alternative idea. You can buy fishnet, natural or colored in many stores. Smaller one are available at Dollar Tree and can be scattered and stacked to camouflage the ductwork. Larger ones are at Hobby Lobby, Michael’s, Walmart and Target. They are easily dyed and go with a tiki look. Best wishes ☺️