Actually it IS possible to add additional RAM to an RCA Cambio. However you will need a defective "donor" machine (for the two 1GB RAM chips). And SMC soldering skills (Surface Mounted Components). So you would have to decide if the purchase of a defective Cambio AND Desolder/Solder to mount them to the board is worth the effort. The Intel Atom processor can take up to 8GB RAM (architectural limit). And there are supposedly some models of the Cambio that do have 4GB RAM. Also, on the main motherboard, there are two empty RAM chip sockets for the 3rd and 4th GB. These were probably added for future models that never surfaced, or at least didn't surface in America.
I did the mod on mine just out of curiosity and while it did run a bit better, the biggest problem is that RCA cheaply loaded the Cambio with a 32bit copy of Windows 10 and RCA did not build a 64bit image that anyone can find. Experiments have had both varied, and with rather bizarre results. One user reportedly was able to load a 64bit Windows 10 image, but seemingly was unable to utilize the touch screen. Basically it became a low end PC and no longer a tablet. So, if you do want to tinker, just be warned the results might not be "predictable" and that the effort is not worth the cost as you can easily find 4GB and more tablets for a decent price.