For quite a while. As long as the ASIN metadata field (EXTH record 113) of each book (the same book on each different device) has the same number in it (does not have to be a valid ASIN number), you can sync the Furthest Read Page (but ONLY the Furthest Read Page).
EXTH record 501 cannot contain 'PDOC', it must contain 'EBOK'.
You used to have to use Mobi2Mobi to change the EXTH records, but now calibre will give it a fake ASIN (based on the UUID) if it doesn't already have one when you format shift.