It's not. For example, so far, all models of the ipad tablet do not support wireless charging. In addition to the ipad, whether other brands of tablets support wireless charging also depends on the specific model, and not all models can be.
No.
None of the current iPad models support wireless charging. Both the latest 11-inch iPadPro and 12.9-inch iPadPro require a USB-C connection to a computer or power adapter for charging.