There are no official inquisitor renegade militia miniatures. But there is a professional unofficial miniature out of Eastern Europe (i think Russia). It is only a tad under 54mm.

Vraksian Guardmans with chainsword (commision painted)
Vraskain Captain. I used the Forgeworld Ork Commando torso, backpack and head to kitbash this mini. Works well i think (commission painted).
Vraksian Guardsman in reinforced carapace. I got this mini from an Australian wargaming forum. I just need to add a silencer to his pistol.

My favourite renegades in the fluff are the bloodpact. And i enjoyed the book where Gaunt’s ghosts come up against an entrenched bloodpact army.

Bloodpact Trooper. I’ve used a fan-sculpted head by Lord Borak at the conclave forums. I also extended the legs to match the height of other inquisitor minis.

Other manufacturers have also made models that are suitably renegade militia.

This model i got from Etsy. I think it is called the survivor.