World locked rendering isn't a requirement for smartglasses. Some existing ones in glasses for factor do have more limited visual positioning systems. In more obtrusive formfactors they have positioning suitable for world locked.
for assistant glasses to be useful, you need to know who, what, when, where for each operation that the user cares about. In the experiements that I ran, that took about 35 watts continuous on the headset (using a jetson) and at least 2 big GPU machines in the backend. This was in 2024, so perhaps its not quite as heavy now. but its nowhere near 130mw