A Computer is a necessity. Not only do you need a computer to upload your website, but trying to navigate the domain registrar?, and host? really can not be done on a smartphone or tablet. I don’t even think there is an FTP? client for mobile devices, so that is another reason why you would need a computer.
The computer can be anything that is safe to use on the internet. Since Windows 10 is no longer supported by Microsoft, you might not want to use your Windows 10 PC to use the internet. If you have no other computer, then I would recommend that you install a new version of Linux. While there will be some learning curve, it is not nearly as bad as you would think. If you have a ChromeOS PC, this will not work neither. Again, you would need to install an FTP client, and you simply can’t find a FTP client plugin for the Chrome web browser. If you are looking for an Linux OS, consider Linux Mint or Zorin. If you need help in installing Linux, consider going to my Installation Guide.