The Vidyard employees have been working remotely since way before the pandemic. In the below link they give tips on designing an effective onboarding process.
Using video footage is key as the new employee can watch at their own pace and revisit if a refresher is needed.
Through the use of video, I particularly like that the CEO/founders can introduce the company/agency and a new employee can get to the know the personality and origins of their new place of work.