Feel your pain. Got a Huawei phone mid 2018, without knowing that a few months before they removed the option of unlocking the bootloader (I was under the impression before, that all Android phones could be unlocked).

Granted, this was just a quick replacement phone when my previous phone just decided randomly to die one day.

At least at the moment it seems that Huawei is an outlier, no such issue with Xiaomi phones.