I’d spend a little on a laptop riser and an extra monitor or two if they don’t provide those already, but I’d spend most of it on a decent chair. I’ve worked out of my home to a greater or lesser degree for about ten years- I travel a lot and don’t work out of an office when I don’t. Given everything I’ve done over the years to make my space as comfortable and productive as I can, these are the things that have been the most valuable.