Having reached the end of this thread, I feel it would be helpful to clear up two items.
>> 1. If the L1 charger is "this" big, then a 10 kW one should only be about "that" big.
The L1 box is not a charger. It's a safety connection relay. The actual charger is in the car. So you can't use the little EVSE as a reference if you are going to build something else such as an actual charger.
>> 2. The non-isolated chargers are not all that big. We can just drop an isolation transformer in ahead of it,and we're done.
Transformers work in a very specific way. More power, more transformer. I learned in college that one way to gauge the capacity of a transformer was to weigh it! A quick search turns up a range of numbers but a ballpark figure might be 1 pound per watt. See where this is going? I did a little more looking, and a nice example of a 10 or 20 kVA transformer is that one sitting at the top of a nearby telephone pole. If you think about putting a pole transformer under you hood, you will begin to appreciate the problem.
Now, the good news is that the foregoing is for 60Hz. That's your plug-and-play solution. If you up the frequency considerably, you can use smaller transformers and save a lot of weight. The price you pay is for all that fancy electronics to change 10kW of electricity into high frequency AC to go through the transformer. At that point you may as well finish the job with rectifying to DC and adding regulators. Now you have an idea of what they're putting inside those quick chargers, and why they're so costly, and that there really wasn't a free lunch, after all.
