AngularDart is sadly basically dead these days at least publicly. It still runs all of Google Ads so it’s very well maintained internally I imagine but it’s officially unsupported publicly at this point which I agree is a shame.
Flutter for web is at a weird stage right now. I think once AOM, WASM-GC and WebGPU are in place and well supported across browsers it will be a very different story but thats probably a year or two away at this point.
The public version of AngularDart (i.e. not the one that Google maintains for its internal teams) is in maintenance mode, which is a shame because it was awesome.