Honestly it's not very applicable in the US at least since ethnonationalist control of any institutions beyond small localities is impossible. Not so sure about Europe, I know Estonia has an ethnonationalist party in charge.

For the Americans they should instead learn from the way indigenous communities in Mexico have taken up arms and secured their towns from cartels and feds alike. Vice has done a number of videos on the conflict in Mexico featuring them lately.

Using geographic checkpoints to enforce local sovereignty and make it extremely painful to enforce control should be the goal. Will the army be able to force control of belligerent localities? Sure, but the harsher the methods the more will sympathize with anyone fighting back. As the US deteriorates it will be less able to maintain its army and its force projection will no longer even extend across its own country.