Yeah this thread is making a lot of assumptions. Maybe the machine has been ordered, or they need to do HR type onboarding for the first few hours, or any number of reasons. Every job I've ever started I bring my own machine just in case and it has been fine.

It's only a red flag when they specifically ask you to start doing work on your own machine.

I am going in with a positive attitude that this is the case, but 100% with you no actual coding starts on my personal machine.