I have had great success with Pearce grip plugs and they have not budged no matter how hot of a round or how many I put through the gun. It does make it a little nicer for quick magazine changes without taking my eyes off the target. Other than that night sights are a great addition, but I am still deciding who to go with for that so no real advice from me there.
I also have the g23 gen 4. I bought a fully cantable holster with a Velcro attachment. It is very versatile. I also have a Don Humes leather iwb holster which is not cantable but is still comfortable for most use.