Can the magsafe duo charger be used with iPhone 8

No. The iPhone 12 is the oldest iPhone compatible with MagSafe

Yes. See the following from iPhone SE - Technical Specifications - Apple

Wireless charging (works with Qi chargers14)

But be aware that It won't magnetically attach to the iPhone 8. Also see the following from How to use MagSafe Duo Charger with your iPhone and Apple Watch - Apple Support

When charging a non-MagSafe Qi-compatible device with a MagSafe Duo Charger, power is reduced and charge times might be slower than on a typical Qi charger. 

quinten37 wrote:

No, the iPhone 8 is not compatible with MagSafe

The iPhone 8 is not compatible with MagSafe, but a MagSafe charger can be used with any Qi-compatible device and a MagSafe charger can be used to charge Qi-compatible devices, including the iPhone 8.

No, the iPhone 8 is not compatible with MagSafe