The benefit of LiFi would be the exact opposite: in a congested signal space, that it's actually easy to mostly shield an area from it - i.e. you and your neig

The benefit of LiFi would be the exact opposite: in a congested signal space, that it's actually easy to mostly shield an area from it - i.e. you and your neighbor can have LiFi APs screaming out signal and a simple plasterboard wall would almost completely shield the interference. It strikes me that 400nm UV LEDs would be a good choice for this application: we can't perceive 400nm, it doesn't penetrate cells (FYI: this is why all "LED" sterilizers are snake-oil), and most importantly the UV spectrum is almost entirely blocked by regular glass-windows so the sun wouldn't interfere and the signal would attenuate to nothing at the bounds of a building.