I also have 64GB on my work T480 (non-s) despite "max" being 32GB.
The Lenovo-reported max RAM specs often do not take into account newer larger memory modules released after the laptop (or at least I believe this is the reason for the discrepancy).
Intel has been absolutely incorrect on this a few times. Quite often there is a conflict in ranges that the ACPI spec included in the system firmware can't deal with, but if an operating system is clever enough it can work around the problem.
It may require some ACPI trickery, but it absolutely is doable. If the firmware guys are super lazy it may just work without ACPI trickery.
I also have 64GB on my work T480 (non-s) despite "max" being 32GB.
The Lenovo-reported max RAM specs often do not take into account newer larger memory modules released after the laptop (or at least I believe this is the reason for the discrepancy).