Thanks Uma. I have mentioned all the alternatives in the blog post.
First of all, I would highly recommend you to use Chipotle peppers in adobo sauce if it’s available. It makes a huge difference. Plus its easily available on Amazon and in grocery stores.
But if you don’t have the option, you can use –
1. Tabasco Chipotle hot sauce
2. Tomato paste, Smoked paprika, and Cayenne pepper
3. Or you can make your own with tomato ketchup, vinegar, chipotle powder, cumin, oregano, garlic powder, and salt.

Hope this helps.