I guess that I was a remote employee that needed to onboard at a new company at one point. When Redgate Software bought SQL Server Central, I lived in Colorado and the company was (mostly) in Cambridge, UK. However, I was hired mostly to continue the same work I did at SQL Server Central, so I didn't really on board with the company. I signed a contract, and set up payroll paperwork, and that was it. I used my same workstation and laptop, albeit with a new account, password, and VPN, but almost everything was the same for me.
Over the last two years, we've hired many people at Redgate, with most of them being brought onboard remotely. Plenty of them have never seen any of our offices, and quite a few didn't meet any other employee in person for months. Our blog posted a couple of stories from people we've hired in the last year about the remote onboarding process.
The stories are a bit light on details, but I know that we send out packets of info and boxes of equipment to people, and we use Zoom and Slack extensively to help people get themselves configured and set up for work. I also know that our managers are good about regularly reaching out to people and connecting them with resources if they need assistance.
For many technical people, I think getting a pre-configured machine and then credentials would allow us to get working easily. A URL or path to source code and server names ensure we can work on a database or a set of code. Asking a few questions of current employees should solve any minor issues with connecting to development resources.
I don't envy anyone that starts a new job without being able to see or talk to someone in person at a new company, doing new work. However, I do think this is a process that is likely to continue for some time. Even those companies that have open offices and employees available likely have learned how to send someone packages and get them productive quickly without needing to schedule everything face to face. Even most signatures can be handled electronically these days.
I do think we miss something by not getting together, at least periodically. I know I enjoy traveling to the Redgate offices, and I think most people would gain something from being in the same room as their co-workers some of the time.