I can't answer that for your PogoPlug hardware.
Supporting precompiled FTL binaries for ARMv4, ARMv5 and ARMv8 was added with FTL v5.3.
ARMv6 with hard float(!) has been supported way back.
While v4 and v5 definitely lack hard float, v6 and v7 sit in between, as hard float is optional with them. Afaik all Raspberry Pi CPUs (including the v6 varieties) support hard float.
I am not sure about the PogoPlug hardware, though.
You probably could check your CPU Features for that:
cat /proc/cpuinfo