I can't see how this would go well. Chrome OS has been a big flop, and pushing that onto phones is just going to pile more disadvantages on top of that.
The everything-as-a-website concept is fatally flawed anyway, as while it is often possible to find a single-purpose site to do a specific thing such as converting file formats, you're completely at the mercy of an unknown third party and their privacy policy (as well as promise not to tamper with your file) if you do. It's a privacy disaster waiting to happen. That, and javascript is a horrible and inefficient language not fit for purpose even years ago, so certainly not on devices with weak CPUs and limited battery.
The everything-as-a-website concept is fatally flawed anyway, as while it is often possible to find a single-purpose site to do a specific thing such as converting file formats, you're completely at the mercy of an unknown third party and their privacy policy (as well as promise not to tamper with your file) if you do. It's a privacy disaster waiting to happen. That, and javascript is a horrible and inefficient language not fit for purpose even years ago, so certainly not on devices with weak CPUs and limited battery.