I want to make my Android app decentralized by integrating with Blockstack. So, I thought to use Blockstack Android SDK on GitHub. However, it needs a web domain for my app as far as I understand from README.md file. So, can I still use this SDK or should I follow another way to achive my goal?
Yes, a web domain needs to be associated with the app for authentication. However, you do not need to host the app there, just a manifest file with an icon. You can use any (web/http) hosting like github pages, firebase. IPFS probably does not work (yet?)
You need to add this domain into the manifest to catch the redirect after the login.