Could this run in Wasm? Even if it was just running it 'headless'? I'm looking something like this to manage layout / animations of text like the DOM to plug into WebGL.

Yes. It currently compiles to WASM but doesn't run. But that's just a matter of plumbing it in properly.

If you were running it "headless" (which is supported), then it would probably work today.

There would also be the option of using Taffy and/or Parley (the layout libraries) without the rest of Blitz.