This something to be aware of. Even if your application could run on older, simpler devices, the FireMonkey runtime has demands of it’s own, over and above those of any application you might develop. Even “Hello World“.
FireMonkey XE5 only runs on Android devices with NEON hardware. This includes my Galaxy SII phone for example but not my ASUS TF101 because this uses the Tegra2 chipset which does not include the necessary NEON silicon.
And now, as well as a relatively high bar of entry on Android, that bar has been raised just that little bit higher for iOS as well. With FireMonkey XE5 now only supporting iOS 6.x and later, 1st Gen iPads are now not supported either, for example.