What I bought from Amazon was a CTEK for $69 and it works great off of the cigarette lighter. Just plug it in after you turn the key off.To add to this informative thread - I bought the Porsche charger and, following instructions here, plugged it into the cigarette lighter, left it overnight. No luck charging. I tried a CTEK I bought 2 years ago. No turning ignition on/off. It just fired right up and later that day I had the 5th green light illuminated. I tried the Porsche charger on my BMW roadster and it worked instantly. It would not work on the Macan and I made sure there was good contact in the cigarette lighter. Bottom line - a regular CTEK, in this case a MUS 4.3, works by just plugging it into the lighter on a 2020, and it's far less expensive than the CTEK branded Porsche charger.
CTEK 40-206 MXS 5.0-12 Volt Battery Charger