Question on First Alert smoke/CO detectors

I am looking to setup the house with some Ring cameras. I'll have 3 of them so I'm just going to go with the Ring Protect Plus as it'll only be $10 more per month in case I add another. I don't feel a need for the secrutiy system itself, but would like to setup the First Alert smoke/CO alarms. I can only find that it "works with the security system", but is it necessary to have the security sytem to use the detectors and have the monitored? My long question is, can I have the First Alert dectectors, without the security system, but yet still have them being monitored since I'll have the Ring Protect Plus plan?