Well, I'm pretty much set with OF iPad and don't really like tinkering with my GTD setup when I should be doing things.
You might try to look at
https://www.nirvanahq.com/tour
I haven't really looked at it myself but I am aware of it.
They are advertising themselves as a web version. You can use your web browser on your mobile device or any computer and use GTD through that means.
So developing a web version is definitely not an easy undertaking. It is not as simple as just taking the OF source code and just wave a magic wand to make it appear as a web site.
But at least you have options.