I implemented a weekly technical training program that morphed into the 250 person org official onboarding. Weekly, I literally just get someone on a VC for 30 minutes and record having a conversation about a technical topic at a noobie level. 16 months later we have 50+ training videos on every topic.
We implement mentors and formal onboarding processes with screen sharing and remote whiteboating sessions, too.
It's not hard.