After digging deeper into the first developer beta of iOS 17, netizen @Aaronp613 found two MagSafe accessories, A3088 and A2781.

A3088
In the iOS 17 Beta 1 code, Apple calls the device “MagSafe Charger”, which is supposed to be the new MagSafe charger or a derivative of the existing charger.
A2781
In the iOS 17 Beta 1 code, Apple refers to this device as the “MagSafe Battery Pack,” which is supposed to be a MagSafe-enabled mobile power supply.

The initial MagSafe external battery is currently priced at RMB 749 on Apple’s official website in China and supports a maximum of 15W of charging power.