Sorry, no Teensy has this much RAM. 256K is the max, in Teensy 3.6.
In fact, I'm not aware of any Arduino compatible board using a microcontroller which has that much RAM. The most I've see is this ChipKit board with 512K.
Arduino and Microsoft some time ago announced a way to program PC-class hardware with "virtual shields". I know almost nothing about it, and so far I've not heard of anyone actually using if for a successful project (which makes me quite skeptical), but if you want to find it just google for "arduino windows 10 iot".