I would take out my personal SSD, put in a blank one and freshly install the needed OS.

Just to conform, and in case I needed a working machine until I found out whether they were serious enough to properly supply the necessities.

If not, then I could carry on with my own "good as new" laptop dedicated to the employer as long as necessary until I had collected enough pay to get an additional one for myself. Nicer one too.

Before even thinking about making any waves.