Aulumu G09 Magnetic Ring Grip | Omnidirectional Rotation | MagSafe Compatible | Aluminium Alloy Construction | Stable Dual-Sided Magnetic Attachment | Includes Handle Ring Phone Stand- Silver

Unrelated but I was looking for magnetic rings for my dual phone setup and this one looks promising. It's $45 on Amazon but you can get two of them for $11 on AliExpress. https://www.amazon.com/Aulumu-Omnidirectional-Compatible-Construction-Dual-Sided/dp/B0DTCWLGWX/