Sure. It's plenty feasible. I've used old laptops, desktops, a server board running naked under my desk with parts strewn about... anything can run your homelab.
The only thing you may have issues with long term in a laptop like that is the battery turning into a spicy balloon. Regardless of whether its healthy, or totally "dead" and wont charge, it can and will still start to offgas and can catch on fire. If it has a removable battery, take it out and run the laptop on a normal UPS that is designed to sit fully charged and plugged in 24/7.