Even the the example at svader.vercel.app/hello-world/webgl/?
Testing on the Safari browsers is currently a TODO, and the library is in general still experimental when it comes to wider browser support, but I would have expected at least the standard WebGL examples to work.
Does it at least display the "WebGL not supported" message?
WebGL works very well on iOS.
If in doubt try https://luduxia.com/whichwayround/ ;P