Estimate laptops in an office

Give a back-of-the-envelope estimate for how many laptops are physically present in a typical corporate office at a given moment. State your assumptions clearly, define what counts as a laptop, and produce both a point estimate and a plausible range.

A strong answer should break the problem into segments such as full-time employees, contractors, visitors, shared conference-room devices, and spare or loaner inventory. It should also account for hybrid work, employees who take devices home, and uncertainty in office occupancy.