Hi there. Great stuff, thanks!
For some reason the device didn't show up with the current configuration (neither on Windows nor on Mac OS)
For anyone who might need this: I got it working by replacing the filters with the two options below (more devices can appear when trying to connect, you only have to select the ELK-BLEDOM from the list)

navigator.bluetooth.requestDevice({
                // commend these lines out
		// filters: [
		// 	{ services: ['0000fff0-0000-1000-8000-00805f9b34fb'] }
		// ]

                // add these lines
		acceptAllDevices: true, // all devices show up, just select the right one
		optionalServices: ['0000fff0-0000-1000-8000-00805f9b34fb'], // this is required to allow using the service
	})

And a question: seems like the controller doesn't support individually addressable leds, is this right?