My workplace has entire fleets of that exact ZBook 15 generation; they are indeed quite well-built, easy to service, and we've got literal boxes full of the little SATA cables (all our fleet units just have M.2 NVMe drives installed). Forget the cheap plastic consumer-class HP offerings, the ZBooks are what you want.
That ZBook 17 G6 is really tempting; I might just replace my OMEN X 2S with it. There weren't any 17" mobile workstation deals this good back when I was laptop shopping in late 2020.