Yes, but immediately change to fascist or communist, it makes everything much easier. For instance my two most sucessful non-allied factions are El Salvador and Iran.

El salvador you start fascist and can run wild on all of central america until the pax americana starts. You can stop this by making America fascist and seeing if you can start a faction with them. Ally with Venezuela as well and use their stregnth to bring south america under control too.

As Iran, go political effort and immediately get the fascist reformer, and start going for the fascist national focuses. From here, invade Saudi Arabia, Yemen and Oman. The allies are cautious to intervene in these wars. In my current run i ended up joining the Axis just because Britain justified against me, but you can stay completely out of WWII.

However, be cautious, if your country you plan to invade is being guranteed, or they're democratic/communist, they may immediately join the Comintern or the Allies the second you declare war and suddenly your war gets merged with WWII and your're in deep shit.