Just going to jump in then disappear again because natural pods are my favourite but I'm on bupe and have another three weeks to go until I can indulge again, long story, this thread is making me crave badly.
Get a coffee grinder that is also a smoothie maker. Powder your pods and add boiling water to the smoothie flask where your pod powder is already from being ground up. Be careful about the pressure and release the cap as needed between mixing, whiz up the powder and boiled water together, then just leave it to sit twenty minutes or so. It continues to darken. Strain through a large reuseable teabag, put the sludge filled teabag in a flask of boiling water for later and drink the first lot.
I have a stovetop expresso maker and sure I done that many times but you can't beat thoroughly mixing hot water and powdered pod in a blender.
I used to add lemon for taste and acidity, grapefruit has some chemical that potentiates it, I never noticed. I don't bother now, just hot water and make your powder first before adding water.
The extraction of the expresso maker seems equal (judging by how much a second extraction in the flask darkens or not), but the impact is less, so maybe more is destroyed.
I'll try sugar with it in January
To the OP, I thought more would be destroyed by repeated times of steaming? It can be made stronger by using less water too. Interesting that it worked, one more method on my to do list.