Fitbit USB Bluetooth Wireless Sync Dongle Adapter FB150 x2 (Salford M5)

I have 2 of these USB-A dongles, probably from my Fitbit Charge HR (circa 2015), if they are any use to anybody who has managed to keep an older Fitbit going.
According to the internet:
"The FB150/FB152OD wireless sync dongle is compatible with these legacy trackers:
• Fitbit Charge HR
• Fitbit Charge (original)
• Fitbit Flex
• Fitbit One
• Fitbit Zip
• Fitbit Surge
• Fitbit Alta (first-generation)" so I don't think it'll work with the Fitbit Charge 2 onwards.
Prefer them to go together.