From what I have experienced, the Nokia X6 which shows as Totoro is a converted unit, but flashed with a custom firmware. That is the reason why it does not receive software updates. So, if you unlock the bootloader, then you can install the official WW firmware which will receive OTA updates. I can confirm that it will even receive the Android Pie update.
Here's a roadmap:Unlock the bootloader - All Totoro devices that I have seen run the July security patch. So, unlocking the bootloader will be an easy task by using the unlock key. You can buy the key here. Download the WW ROM & flash it - With an unlocked bootloader, you can flash the phone yourself. So, use OST 6.0.4 to flash the official WW ROM. Do not use OST 6.1.2 as it will not work. Wipe data/factory reset - After installing the WW firmware, you need to do a factory reset from the recovery mode. This is needed to wipe all data from the device, which can sometimes prevent the phone from booting up.
Let me know how that goes :) This is only for the 4GB RAM variant. The 6GB variant cannot flash this ROM.