Thanks for the reply: it makes sense to me now. Is this the explanation you refer to? Non-Neutral Wiring v Neutral Wiring - #4 by JohnRob
Based on your information, it seems that in a non-neutral setup you could try installing the switch and LED bulb without a bypass first. If that works, great, but if not, and the LEDs are illuminating erroneously, then install a bypass. Is there any risk or downside to trying that approach?
Relatedly, in order to choose between having an electrician install a bypass vs. bring a neutral wire to the switch, what should be taken into consideration? Is there likely to be a big difference in labor, materials, risk of failure, overall cost?