Tell me experts, why is this not practical. Can you put a HTML renderer on an FPGA?

Don't modern browsers already use GPU acceleration?

Do they acceleration DOM parsing, or just media that already has acceleration hooks provided by the OS?

Firefox uses the GPU via WebRender[0]. I don't know what specific things it's used for, but I'm pretty sure it's not any of the DOM parsing. The GPU is used for the actual graphical rendering down the line -- compositing and such[1].

[0] https://github.com/servo/webrender

[1] https://hacks.mozilla.org/2017/10/the-whole-web-at-maximum-f...