Is there a keyboard shortcut to navigate upstack and downstack in the dashboard? seems like something essential but don't see it in the keyboard shortcuts helper menu

It's

⌘⇧↑

/

⌘⇧↓

for upstack/downstack on the PR page. Good call on putting those under Navigation in the shortcuts menu as they currently live under Review. I'll pass that feedback along, no ETA to share but if we decided to implement we will double back and alert you. Thanks!