I don't know that anybody doubts this, but until you can run a browser as a UEFI boot option, you've just created a third layer of choice without doing anything to solve the first two.
You need to have an operating system to run a browser, unless you want to make a browser on bare-metal. I don't think you currently understand the topic very well.
Your project is essentially an incomplete implementation of a shell where all commands are builtins, and the interactivity is limited by what you directly programmed in JavaScript.
What you are trying to make is a lot harder than you think, you first need to emulate a CPU and go from there, not read whatever user types and try to behave like a Linux system, which ChatGPT can do already.