Compatible with the MacBook Pro/Air 2021?
Yes. This mouse fits all devices with USB ports and Thunderbolt (type c) ports.
Where is the USB receiver?
The USB receiver 𝐬𝐭𝐨𝐫𝐞𝐝 𝐢𝐧 𝐭𝐡𝐞 𝐛𝐚𝐜𝐤 𝐨𝐟 𝐭𝐡𝐞 𝐦𝐨𝐮𝐬𝐞, type-c adapter comes in the box.
Left or right hand use?
Right handed ergonomic mouse.