Realme is a company that belongs to the same group as Oneplus and Oppo, namely BBK Electronics. Since it is possible to use the Fingerprint Reader on the Onplus devices after bootloader unlocking and the Oneplus 7T being quite similar in hardware to the Realme X2 Pro, it would only make sense that it should be possible to use the sensor on the X2 pro as well after unlocking.
So this seems to be more a political decision rather than a hardware limitation.
Ways for you to request a fix for the issue are ideally via the Realme Forum, that is the Indian Forum (as they speak English, that more easy for most of us, than using the Chinese forum. And the Indian version being basically the same as the European version as well).
You can comment in this thread:
As well in this one:
Additionally, you can contact Realme Europe via twitter here:
As I already did, as you can see here:
So let's make this Realme great again