SwitchEasy recently came out with a series of "MagEasy" accessories that are designed to add MagSafe compatibility to older devices or to iPhone 12 cases that aren't equipped with built-in magnets.

The MagDoka is a circle-shaped magnetic ring that attaches to an iPhone or an ‌iPhone‌ case using adhesive. At 2mm in thickness, the MagDoka doesn't add a lot of bulk to an ‌iPhone‌, and in my testing, it adhered well and didn't budge, even when used with an upright ‌MagSafe‌ charger that caused a similar product to lose its adhesive.