I have bought android app from play store and now i want to add my MEGA account in it. Is it possible to add any other cloud drive than Google, One Drive or Dropbox?
Unfortunately, MEGA provides no WebDAV connection. See here: WebDAV URLs of Common Cloud Storage Services
You can’t access it with android or iOS app. Only via desktop with their own client to sync the encrypted files to the storage.
You can add any storage provider that allows WebDAV connection to your android app, and of course the named provider in the apps.