> Where is the vertical video app that lets you watch your favorite YouTube/IG/Twitch-type “content creators” on your phone in the same easy/addictive format as Stories?
I think you just described TikTok.
I think you just described TikTok.
YouTube and Twitch though seem to have some of the strongest "content creator" culture and are both still stuck in landscape videos and other sub-optimal phone UI.