What’s the best way to cook tender duck breast? Is slow cooker or pressure cooker an option?

The two cooking methods and three dishes you mentioned are all suited for duck LEGS, not breasts. The legs have lots of collagen and fair well for longer cooking times and higher internal temperatures.

Duck breast meat is ideal when it is cooked to medium rare but enough to render out most of the fat and crisp up the skin. Duck breast meat gets tough when subjected to too much heat and too much time.

Here is the best way to cook duck breast:

https://www.seriouseats.com/sous-vide-101-duck-breast-recipe

Concerning Kenji's sous vide technique, take careful note about starting the searing process in a COLD pan.

If you don't have a sous vide immersion circulator, the best way is to cook it over the stove restaurant style:

https://www.seriouseats.com/for-perfect-duck-breast-get-in-the-zone

If you go with Sohla's stovetop method, pay attention to the author's notes about sound. A good cook also uses their ears and this is one of those moments in the kitchen you need to pay attention to the sounds coming from the pan, not whatever Spotify or Pandora playlist you have blasting.

For duck legs, the best method is do sous vide confit. There are decent instructions at Serious Eats as a starting point.

Best of luck.

Have made duck too few times to give advice.
But the duck recipes by a hunter at honest-food.net give lots of sound advice about cooking skin-on duck breasts in a frying pan...where you can keep track of the cooking process.
Good luck (and save the fat for great potatoes)!