Looking for your feedback! What domain should I pick? 🤔

"tailwindstack" sounds like it's affiliated with Tailwind, and might be close enough to be legally an issue, should Adam feel the need to protect the trademark. (Also maybe not! I'm drawing from experience where I made a game called "Slack & Slash" and Slack asked me to not use the actual product name in the game name. I went with "Chat & Slash" and they were fine with it.)

"tailstormui" has me wondering what a "tailstorm" is. Is it some kind of hailstorm? Is it a typo?

"stormuikit" sounds much cleaner, like a real actual product, though a quick search leads to a few pages about the Apache Storm UI. You'll have to do a bit to overcome that inertia, but I don't think too much.

A note on feasibility: Tailwind UI is Adam & Steve's monetization play on Tailwind CSS, so they're going to be putting a lot of effort into it. When you pick what components to build, you'll probably want to think about and focus on ones you don't think they'll ever build (kanban board sounds good), as opposed to ones you don't think they've build yet (progress bar). If you try to plug those "obvious gaps," you could very easily find that they plug them themselves and leave you without a differentiator.

Alternatively/additionally, you could build similar components to the ones they have, but with a different design theme entirely. There's no reason why multiple takes on a concept can't exist. But you very much want to be able to position yourself as an alternative to Tailwind UI, not an extension of it.

I'd stay away from their name and focus your SEO on their name. stormuikit.com looks and sounds good.