Taking a quick look at [the docs](https://r3f.docs.pmnd.rs/getting-started/introduction) linked above, I see the use of Canvas. Fair enough.
I start using X3D at work in order to enable some cool functionality showing steps to build an assembly in 3D, and it's actually insane how high the performance is. It's all HTML components, so I wrote a super thin React wrapper (essentially the scene needs to be manually loaded once, that's about all) and have been cruising with that.
Effortless to fly, rotate, hide or highlight parts, decompose things into x3d assets, and so on.
It might have issues somewhere, I haven't widely tested browser compat or anything, but it's curious to me how little I see it versus how much I see ThreeJS when it seems that X3D is the more capable platform.