777/747/757/767 have 3 a/ps. There is a requirement to "fail operational" to operate down to DH below 50` and RVR below 125m. 2 a/ps can only "fail passive" therefore cannot.
Under Jars cat 3 C i.e. 0/0 does not exist therefore no JAR operators are so certified.I am not aware of any company in the world that is so certified (stand to be corrected). The minimum is cat 3 B no DH and 75m required RVR.
Both crew members ,the company and the aircraft have to be qualified to operate below cat 1.
A Jar instrument rating only qualifies you to Cat 1.
Depressurisation "issues" are not part of LVO training.