Do you have such hot key to select many items? it is kinda slow to click them one by one.

On a controller it's either LT o r RT (I forget which since it has become muscle memory), and by default on keyboard, the online manual say it is Shift+Left Click or Crtl+Left Click.

I never click when I'm selecting multiple items for swap shop, or mass selling items. I generally just hold "shift + down arrow" to select all, then confirm. I keep the stuff I don't want recycled/sold locked, so I don't ever discard items by mistake.