One obvious option is to build a new police department entirely out of officers poached from the police departments of other counties/states—preferably from cities that manage to have both high racial diversity and low rates of questionable police violence. Other public-servant roles (e.g. postal workers) get relocated between cities this way all the time, being moved to where there’s demand.
Another option is to just have no official city police department (i.e. a group with warranted immunity from criminal prosecution for “exercising one’s duties”), only an informal community watch/militia of regular citizens entirely out of the hands of top-down municipal control. There are functional communities that operate this way, e.g. Cheran in Mexico (https://www.bbc.com/news/magazine-37612083)
I doubt that scales beyond small cities. You would get something far worse with private security. If you have Amazon Prime, you will get the right to refuse to testify though. Fun aside, it should also be noted that the people in your example are armed. I don't think that will meet any love with city dwellers.
One worry is, that looking at Franco Spain, he introduced the Guardia Civil to oppress ppl, and one mechanism was that no officer from the local community was allowed (at that community). That prevented police to fraternize with the local people.
Also, could it not be perceived as a punishment for the police officers to get transfered, like: you did good work so please change city.
Another option is to just have no official city police department (i.e. a group with warranted immunity from criminal prosecution for “exercising one’s duties”), only an informal community watch/militia of regular citizens entirely out of the hands of top-down municipal control. There are functional communities that operate this way, e.g. Cheran in Mexico (https://www.bbc.com/news/magazine-37612083)