title_body: Is there a way to sync reading progress across multiple devices and platforms?
upvoted_answer: As a general principle, no.  But most software vendors provide compatible apps for PC/Mac/Android. So if you will be happy using their reader app, you just install their apps and get synchronization across all platforms. 
  
  For instance, I don't own a Kindle, but I buy ebooks from Amazon and read them on both Kindle for PC and Kindle for Android
  
  The same is true of Kobo.
  
  What this doesn't do is let you sync sideloaded books, or any book not purchased from that particular vendor.