Aura components aren't supported in the Field Service Mobile + LWC pilot. They won't work at all. Lightning web components are the supported flavor in Field Service Mobile.

Xcode and Android Studio are pigs, no doubt about it, at least in terms of disk space. But 10 gigs for two complex IDEs, associated secondary tools, the emulator/simulator images, SDK libraries, and so on really isn't that bad, all things considered. Consider that the last iOS upgrade was as large as five gigabytes, and that's essentially what a virtual device image is, and you can see why there's such a large footprint for the tools.

More concerning is the performance issue you describe. Could you provide more details? What system were you running them on? How much memory is installed? How much memory was being consumed overall? What else was running? Did you try rebooting and going directly to e.g. an iOS Simulator? How was performance in that relatively clean environment?

I run Xcode and Android Studio on a MacBook Pro 13" (2020) with 32 gigs of RAM, and while neither runs <sorry> swiftly, they're still quite usable, without any of the issues you described.

Xcode and Android Studio are the only (good) tools available to run virtual devices, and running the virtual device builds of the pilot apps is by far the best debugging experience available. (We know there's plenty of room for improvement in our debugging tools, but it's still the best DX available today.)

While you could pursue other development/debugging tools, the behavior you describe isn't typical or expected. It's a far better effort to try to resolve that, than to try to replace them.