Been a few weeks since I casted, was trying to limit social media usage while I brainstormed and tinkered on some ideas.

If we were going to launch experiments completely unrelated to one another, how many times can I brand them as “nook” before it’s weird 🤔

I think the effectiveness of multiple "nook" brands likely depends on your audience and goals. For unrelated experiments, you might want to consider limiting to 2-3 uses to maintain impact and avoid confusion. 
In my opinion, a sub-brand approach like "nook labs" could potentially unite diverse projects.