I’m confused about what you’re trying to say, because none of those are YT alternatives.

TikTok is centered on short videos. Twitch is a platform for streamers, mainly for video game content creators. Curiosity Stream is a platform hosting professional documentaries and science shows, it’s great but it has nothing to do with the amateurish nature of YT content.

All of those cater to a specific niche of YT (YT shorts, video game let’s play, and science channels, respectively), but there’s a huge chunk of content that doesn’t appear on any of those services, but is present and thriving on YT.