https://veloren.net/
I'm a bit impartial since I'm a former contributor, but I think it's super cool.
Aside from that, the Bevy game engine also uses wgpu on non-web, but afaik no game of particular significance or player base has shipped with it yet. I think the biggest user of it is actually a software tool for mining (the hardhat kind), but it's a "call us for a quote" kind of thing so hard to tell how big it is.
That's kind of irrelevant to the adoption potential of WebGPU.
Those examples you gave are not comparable at all, ativex and flash are way, way higher level, don't operate at all like graphics API middleware.
PNaCL was a WASM alternative design, which thankfully lost as WASM is much more flexible.
My point is that WebGPU is way better positioned than any middleware, it has industry backing and official support from all relevant platforms (or plans for it).
It's also benefitted a huge amount from hindsight.
Aside from that, the Bevy game engine also uses wgpu on non-web, but afaik no game of particular significance or player base has shipped with it yet. I think the biggest user of it is actually a software tool for mining (the hardhat kind), but it's a "call us for a quote" kind of thing so hard to tell how big it is.