Denmark, among others I assume. Using your laptop, without external monitor and keyboard is only allowed as an exception, even when working from home, and only for a short period of time.
You can use the laptop monitor as a secondary display. It's a pretty good law, which forces employers to provide you with an ergonomically sound work environment. You're also required to have a height adjustable desk and chair... and a window.
A window is amazing! My first 3 jobs were window free as were jobs 7 and 8.
I've had 9 jobs total in the 25 years I've been working professionally and those 5 windowless jobs, account for about 5 of those years. I burn out pretty fast in the dark.
Your employer is legally required to provide you with chair, desk, keyboard, monitor and mouse if you work from home and don’t have these things already.
During the corona lock down my boss told us to get anything we required from the office. If you couldn’t pick it up, an intern would take the company van and deliver anything you’d need.
One option was to ban working from home, which was my employer's official stance.
On 13 March, we took from the office anything we needed (monitors, keyboards, mice, desk chairs). No-one said they didn't have a desk, so I don't know how we would have handled that.
You can use the laptop monitor as a secondary display. It's a pretty good law, which forces employers to provide you with an ergonomically sound work environment. You're also required to have a height adjustable desk and chair... and a window.