There is no "verified" or official Facebook Messenger app for the Nokia N800.
via verified third-party Linux-based workarounds, though official native support does not exist. facebook messenger for nokia n800 verified
Verification Checklist (I did each):
Q: Is there any archive of the "verified" Pidgin package?
A: Yes, you can find .deb files on repository.maemo.org, but they only work if you disable SSL verification—which is insecure. There is no "verified" or official Facebook Messenger
Facebook Messenger Availability for Nokia N800 facebook messenger for nokia n800 verified
However, you can still access Facebook Messenger on your Nokia N800 using the mobile web version. To do this: