Ask HN: How does your company onboard engineers?

I'm curious how do companies onboard engineers and what are the solutions out there.

I'm not referring to administrative onboarding tasks such as setting up a Slack account, setting up an email, ensuring all terms and conditions are read and signed, etc. I'm referring to things like: - familiarising new engineers with the codebase, - doing their first coding assignment in the company, - the software architecture & design, - development workflow (e.g. if the team uses master-develop branch model or feature branches to commit straight to master), - and if there are internal tools, how do you onboard new engineers/analysts on how to use them?

Perhaps big companies like FAANG build their own tools to do this but I'm equally curious what smaller companies do. The company I'm at uses READMEs and wikis, which are basically data dump and a checklist of things the new engineers should complete. Are these really the best solution out there?