IPA (IoT Profile Assistant)
Updated
The IPA is the SGP.32 component that relays messages between the eIM, the SM-DP+ and the eUICC. It can run in the device (IPAd) or inside the eUICC itself (IPAe), so that simple devices can use remote provisioning without new firmware.
In practice
When choosing modules for an SGP.32 project, check whether the module includes an IPAd or whether you need eUICCs with an IPAe: the answer decides which hardware you can reuse.