Maybe private pins?

No, not for private chats.
This is a local-only pin that you can make on any comment you see (not limited to yours only)
This is to take notes of something important, maybe a funny video you found that you want to show to a friend that's coming over later, in a very active chat so you won't take ages scrolling back up, it's a pain. Nobody can see it except for you, and you can jump back to that private pin whenever you want.
You can add and remove pins whenever you want.
Also, make it so privately pinned comments have a Blue pin on the right side,
and same for the publicly (the normal one) pinned comments have a red pin on the right side. Would be very good.