I would guess you would owe some agreed value of the PC at the time you received it.

From what I've seen where I work the majority of "work" computers and laptops don't get returned if the employee separates for whatever reason. So I can see some companies wanting to make it a formal loan or have some means to recover the lost value if it isn't returned. My employer doesn't, because the residual value of a 2-3 year old laptop is not even worth anyone's time beyond making a few perfunctory requests to return it.

Eh, the requirement to return your work-provided laptop is about as strong, legally speaking, as a requirement to pay back the value of it when you leave. Perhaps even stronger (because a work laptop is never really even a loan to you). I would suggest your workplace is a bit of an outlier: most places I'm aware of make pretty sure the laptop is returned, even if only because of the risk of company information leaking out otherwise (some places I know might let an employee keep an old laptop that's being replaced after they have wiped it, perhaps with all storage removed entirely).

Yeah, I've generally had to return laptops, unless the company itself is closing down (startups) or such (which I've been "fortunate" on, I once got to keep a nice iMac 27" and 27" Apple display, and then an M3 Max 96GB MBP). But usually monitors, other accessories are "you can keep those".