Depends what you mean by “FOSS Laptop”

FOSS OS: easy— you can put Linux on most computers, even old Chromebooks

FOSS Firmware: Some (eg system 76)

FOSS Silicon: Unsure/limited if you want to avoid proprietary hardware like Intel processors

https://system76.com/laptops

https://www.pine64.org/pinebook-pro/

https://shop.nitrokey.com/shop?&search=nitropad