Yes, the ARM server spec (SBSA) requires UEFI and ACPI, so it's standard there. And *anything* running u-boot can have u-boot expose an EFI interface for the OS to make use of, although it's most commonly used on the Pi - unfortunately this still usually just passes up a device tree rather than using ACPI. There are actually ARM client systems that are natively UEFI+ACPI (the old Windows RT platform, but also modern Windows for ARM laptops), so it's more widespread than you'd think. I believe most modern Chromebooks still use ACPI even if they don't use UEFI, but I haven't verified that.