This permanent transition from CPVC to copper are adapters shown at minute 4 in this Youtube video: https://www.youtube.com/watch?v=6oL2TBel5S0 Sweat copper fitting, screw in cpvc to copper (with dope), last....glue on CPVC.
Easiest would be CPVC to copper sharkbites. I'm still a bit leery of sharkbites where a failure could be catastrophic.....just my old school curmudgeon diy opinion. https://www.youtube.com/watch?v=gToGpVqorZA