In Google Books, I can pick-up reading where I left from a different device. Please consider adding Continue Reading feature on Android / Adobe Reader on desktop. The document is a book stored in the Adobe Cloud.
The main reason why I am using Adobe Reader for Android and not Google Books for PDFs is because Adobe has Text Reflow mode which makes it easier to read a book on a mobile device by reformatting the text.
Mobile link is really helpful and if you can add continue reading it will be better.
Adobe Acrobat Reader maintains the page number where pdf was closed. You can upload a file to Document Cloud. Page number will then be synced across all the devices.
Adobe Acrobat Reader