Strangely, I thought I remember being able to use breakpoints on https://cloudflareworkers.com/ - I thought it handled inspector messages in a nested loop until receiving debugger resume command - since the beginning but I guess I must be mistaken... Maybe that was just an idea we had back then.
Don't know about webcams - usually (unlike in OP's case) those already have good OS-level support, but I did port gphoto2 to Wasm+WebUSB for access to DSLRs & mirrorless cameras: https://github.com/GoogleChromeLabs/web-gphoto2
Browser ports can't integrate at OS level, they're intentionally separated today, but given that e.g. Node.js has WebUSB support (https://github.com/node-usb/node-usb), I guess you could make a layer that exposes such Wasm drivers as native to the OS. Could be a fun experiment.
Ah, I see. That would be interesting, but removes the cross-platform compatibility from the equation, which, for me, is the most valuable piece of WebUSB and other similar APIs.
Glad to hear! If you want to give it another try, you should be able to use my linked libusb fork in any app that depends on libusb, and compile that with Emscripten.
I didn't see it but did think about it. I think it should be possible by wrapping WebUSB into something like Comlink, e.g. I know Surma experimented with allowing Comlink to be used with WebSockets: https://twitter.com/dassurma/status/1218207376899235840
Comlink takes care of the RPC part of any API, so you only need to choose and hook up a communication backend.
With guiding you're usually aiming for 5-10 minute exposures per frame. That usually results in each frame having at least several streaks. Sure, those are technically still short and can be cancelled out, but astrophotography is already challenging enough and has plenty of other noise sources without adding more fuel to the problem.
And that's now, when we're not close to the planned tens of thousands of satellites by Starlink above, and other vendors like Amazon only starting to plan their similar programs. That's why early feedback is important - otherwise the sky will be ruined in the best case for decades to come.