It's a Linux container, so no emulation there - but it's still a fully separate user space that communicates with the rest of the system via a bridge in the same way a virtual machine does.
There's also Waydroid, which works by implementing things like Wayland/PulseAudio clients directly inside Android compositor/sound system, but I haven't ran it on the Librem 5 yet (I know that some people are using it on the PinePhone).