Now that Google supports OBi can we port a landline to Google Voice for use with OBi202 ?
No. Google Voice only ports in mobile numbers.
You can attempt to circumvent this restriction, with no guarantee of success: first, port your land line number to a prepaid mobile carrier, such as AT&T GoPhone or T-Mobile (not one of the Mickey Mouse little MVNO carriers). Wait at least a few days for the port to be broadcast through the telephone networks and for the carrier databases to be updated. Make sure your number is now correctly able to both make and receive calls and text messages.
Then, thoroughly read the instructions and FAQs in the link below, and initiate the port into GV. When you do, it will test your number for portability. You can't test it until it is a mobile number. Note that the #1 reason that ports fail is incorrect user ID and PIN information supplied by the user (you). Verify this information with the mobile carrier before you submit it. For example, GoPhone account numbers are not displayed anywhere accessible to the user; you need to contact them to get the information.
https://support.google.com/voice/answer/1065667
Yes of course.
Is it the same to transfer from another voip carrier like Lingo? Or can a direct transfer be made?
Unless Google has changed the policy SteveInWA is right about not being able to port "land line" numbers to GV.
VoIP numbers are considered land lines, so, the same limitation applies.