Your comments

Let's phrase it this way. How much of a bounty would persuade you to implement this feature?

Personally, if this were implemented using https://developer.chrome.com/extensions/storage (so that it's built into chrome sync), it would be worth 100 USD to me. Of course, there are many edge cases that make it difficult (different computers synced to the same account my have different sets of tabs, and I'd want the Tabs Outliner solution to be intuitive and robust. That's a bit of a steep commitment, but I love my tabs :) I'm others would be willing to commit to something like "half now, half when it's done". To be clear, I'd be willing to commit this to you whether or not you open source the extension--somewhat as a thank you for your work so far, and as motivation to make it that much better.

Somewhat relatedly, how do you accept donations?