It may be possible to charge a Fusion Battery in a Hero 5/6 charger...with a little surgery : r/gopro
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How to Charge a GoPro Fusion - GoPro Batteries & Power
Used GoPro Fusion | MPB
Action Battery Grip, Red - GoPro® & other Action Cameras | JOBY
2pcs 2720mah Gopro Fusion Battery Accu+dual Usb Charger With Type C Port For Gopro Fusion 360 Degree Camera Asbba-001 Battery - Digital Batteries - AliExpress