I don't know how many of them vote for the far right, but why on earth would they vote for NUPES? Mélenchon constantly attacks them, he's on auto-blame mode.
A general idea of the vote of police and military https://twitter.com/Cluster_17/status/1544352151467528196?la... (to be taken with some distance, it is a poll from cluster 17)
Note that Melenchon was proposing to hire 10,000 more policemen