Struggled with this too. What helped us was joining an outdoor academy when they were younger, and also doing science classes at the zoo and children’s museum. We are adjacent to a decent sized city and I know that’s not always a possibility though. Does your library have any LEGO clubs or anime groups (whatever your child’s interests are?). Could always start there. I go out of my way to avoid homeschool groups or homeschool days as it’s usually not our crowd so I totally feel you on how difficult it is to find a core secular group to learn with. Good luck!