How often do you want/need the 300+ mile range in one go? E.g. going 150 miles somewhere then coming back, or a 5+ hours 300+ mile journey to a destination?
If it is edge/fringe case and not that often, then IMO I wouldn't base my buying decision on that, rather look at my normal behaviour and does that tie in with the ability to charge for 10-15 mins. If you look at the EV6 you are talking about that will easily charge at 120kW and way beyond, but even at that lower speed that is 2kWh per minute or 6-8 miles per minute of added range, so a 15 minute stop which is barely enough for a toilet stop, and to grab a drink etc and you've added 90-120 miles of range, which means that 300+ mile range really isn't needed for the most part, again unless you like driving for 5+ hours non-stop.
Other car options depends on budget, how long you want to keep the car, what mileage you do per year, what style of car you prefer etc. Far too many questions to ask so it is best if you indicate what you like/want/need, other than focusing on the range alone.