Is there anything to build?
It depends on the version. The CM4 arrives assembled according to the maker, but the battery isn't listed as included, so check the Amazon listing. The CM5's Amazon listing says some assembly is required. Once it's built and charged, connect it to your Wi-Fi. You'll still need to set up the bridge code that connects it to your AI assistant. Our setup prompt can guide you, but it takes some technical skill and isn't guaranteed to work first time.
Does it need a separate Raspberry Pi?
No. A Raspberry Pi compute module is built in (CM4 or CM5, depending on the version you pick), so you don't need a separate Raspberry Pi. Check the Amazon listing for what's in the box, including the battery.
CM4 or CM5: which should I get?
It's the same robot either way. The CM5 is Raspberry Pi's newer, faster compute module, so it handles camera and voice tasks more quickly. The CM4 version costs less. If the budget stretches, we'd pick the CM5. Check both on Amazon for today's prices.
Can it go up steps?
No. It rolls on wheels, so it's for one floor at a time. Thick rugs and high thresholds can stop it too.
Why does it cost more?
You're paying for it being mostly built, with a Raspberry Pi built in, a screen face and voice built in. If you enjoy building, the kits are cheaper.