In the United Kingdom, police officers generally do not carry firearms. I would like to see some jurisdictions try that here. Anybody who shoots a cop would be shooting an unarmed person. That should carry long sentences and would sit well with juries. I think it is worth a try, but I am not a cop, so it’s easy for me to say.
Maybe unarmed cops could wear a different colored shirt, so prospective shooters would know they are dealing with unarmed officers.