How can I view my backed up messages from a stolen phone to an android phone because I don't havr any other apple device yet

Unfortunately, it's not possible to directly restore an iPhone backup from iCloud to an Android device. iCloud backups are specifically designed for Apple devices and use a different file format than Android devices.

However, you can get some data such as Contacts, Calendars, Bookmarks, Notes, shared photos, iCloud Photos, and emails. Each device syncs to the email account server which may be Google, iCloud, AOL, Exchange, Outlook, Yahoo, or any Other. Please see the pic below

Download them from the email account that you had added to your iPhone.

If you had enabled iCloud Photos then log into https://www.icloud.com using your Apple ID credentials on any web browser and download all the photos to any device.