Well, there are some “arm” related ROOT architectures:
linuxarm -> 32-bit ARM Linux with gcc >= 4.8
inuxarm64 -> 64-bit ARMv8-A (AArch64) Linux with gcc >= 4.8
There exist also “ios” (32-bit armv7) and “ios64” (64-bit armv8/arm64) architectures, but they are Apple iOS specific.
The general problems might be:
- too few RAM on Raspberry Pi (1 GB RAM plus some “swap” would be nice)
- you will probably need to cross-compile ROOT -> I don’t think this is really supported
See also: Cling on arm?