An updated version of Microsoft Surface Pen
Galaxy Note 10 Plus-Pen.
In this JerryRigEverything tear down of this Galaxy Note 10 Plus-Pen.
To the side of an iPad Pro, sports a similar charging coil. You may check it out in the picture below from the i Fix it tear down. The Surface Pen already magnetically attaches to Surface notebooks, albeit without charging, so this FCC filing is a indication of this feature to come.