Is there a problem to get any decently built laptop and put Linux on top of it in your own? You can argue that it's better to get laptop with Linux pre installed, but I don't 100% agree since Linux means freedom in choosing stuff you need, so it's better to install distributive you like than default Ubuntu. Also don't count much on the customer support when it comes to the Linux laptops, it's common for Linux user to handle possible issues independently. So I don't see a strong reason to get laptop with pre installed Linux limiting yourself in other terms, such as accepting worse hardware and build quality (since there are not a lot of Linux based laptops on the market, and so you won't have many choices, so don't even compare for example system76 vs hp x360) and limiting yourself by Ubuntu distributive.