I know of a few in South Orange County. Were you looking to go simple, mostly low key classes and fellowship, or more “schoolish” with field trips, assemblies, science fairs, etc? Here are the four I know of.
Calvary Chapel PSP, Costa Mesa, keeps records, some field trips/activities, no classes for elementary
South Orange County Christian Homeschoolers, meets at homes and parks, laid back, lots of CM moms, does not keep records, offers low key classes
Saddleback Christian Academy, Mission Viejo, keeps records, LOTS of classes, activities. More commitment and cost, more “schoolish”
Crown Academy, Rancho Santa Margarita, does not keep records, lots of classes
I have personal experience with each of these so I may be able to answer questions if there is something specific you would like to know.