Most people with a Rasp Pi usually run a Bitcoin node. You don't get paid for this and it actually used a lot of bandwidth but you keep Bitcoin decentralized by doing so.

Regarding if it's profitable to mine? Consider this. Most people with GPUs and ASICs are barely profitable with 0.12kwh power. And those are high end devices not a portable mini CPU computer. Don't think there is anything out there worth mining even with free power.

If your ISP doesn't give you limits just run a Bitcoin node. You will need a large HD however.