I am looking for a tiny 3-Position DPDT Switch ON/OFF/ON that is super easy to toggle.

The ones I have seen are very stiff and hard to switch.

The others issue is it needs to be 10mm Square or smaller.

Any help would be greatly appreciated.

 

How much current is required?

 

Not exactly sure. It is a small RC Motor that runs in 2 AA Batteries.

 

Tough to recommend anything without actually trying.
Unfortunately I can't help with this.

 

While these don't specify their size, they're palm size. That might give you enough of an idea to go on.
https://www.amazon.com/MTS-203-Position-Toggle-Switch-Quality/dp/B0799JV8GN/ref=sr_1_7

 

This one has an image that shows 12mm X 13mm X 9mm. Center off - 5A capacity
https://www.amazon.com/Twidec-Momentary-Miniature-Waterproof-MTS-223-MZ/dp/B07VK46JQ3/ref=sr_1_10

 

Both toggles are rated at 5 & 6 amps at 125VAC but they should be good for 3V double A batteries.

 

Slightly smaller:
https://www.amazon.com/DMWD-Momentary-Positions-Waterproof-Industrial/dp/B0C969FDS6/ref=sr_1_16

All found on Amazon. Search "miniature DPDT Switch on - off - on.