Unsolicited feedback (or I guess solicited reading the post again): Juypter Notebook experience got me to click because I thought this might be like a Deepnote alternative

But the only screenshot on the Github page was decidedly not that. It wasn't showing something very appealing visually, or immediately obvious in terms of necessity for a tool calling its competitors ugly and bloated

I don't use any of the ones you listed so maybe they're even uglier, but I would maybe tweak the pitch and make it clearer who this is for