It might be a bit more complex than that. I've written about the storage mecanics behind Widevine, and the Poco seems to be the only phone in the world to have been whitelisted L1 with an OTA, and the only one where certificates can me manipulated (backup/restore).
- On Sony devices, DRMs are stored on a hidden partition that is wiped on unlock...
- On OnePlus devices, it's on a chip that can't be read when unlocked, but is reversible...
- Samsung have Knox, which is an e-fuse that is blown when unlocked and disable some apps, cannot be reversed...
On Xiaomi.eu ROMs, I suspect that the liboemcrypto file (used for reading DRM) isn't able to check for L1 since Chinese phones can't be more than L3.
- I don't know if the subject has been covered before, and if a port of the EEA ***** has been attempted
- With 9.8.22+ being Q based, this isn't possible anyway.