Currently it is a no go if you plan to target mobile devices.
Only the latest version of iOS supports it, on Android it is a joke with Chrome blacklisting many handsets[0] and Windows Phone only partially supports it.
[0] You can re-enable it via developer flags, but no normal user is going to know about it.
A minority of drivers/GPUs are blacklisted on desktop, and you have to deal with less than 100% WebGL coverage in any case. But yeah on mobile it's a sharper "reasonably recent devices only" division.
Be careful to interpret the stats there correctly. Eg when you leave just the specific category checkmarked, the graph shows ios-smartphone webgl support rate at 79% and android-smartphone rate at 75%. The percentages in the sidebar are just browser shares and not WebGL support rates.
Only the latest version of iOS supports it, on Android it is a joke with Chrome blacklisting many handsets[0] and Windows Phone only partially supports it.
[0] You can re-enable it via developer flags, but no normal user is going to know about it.