Kinda :/ on there not being a GPU permission (that I can find in the post or the docs); GPUs/GPU drivers have been a vector for some pretty nasty attacks in the past...
Edit: I believe the bug you linked below (https://bugs.chromium.org/p/project-zero/issues/detail?id=20...) can't be exploited through WebGL or WebGPU in the browser because all GPU access is remoted to a separate process with a special GPU sandbox. I don't know if Deno does this but it should.
[0]: https://bugs.chromium.org/p/project-zero/issues/detail?id=20...