Head- and tail lights definitely help make bicycles visible from the front and back, but what about from the sides? The handlebar-plug-replacing SideLights are designed to address that shortcoming, plus they serve as headlights, tail lights and turn indicators.
These look cool. I purchased the Cycl Winglights some years ago and thought they’re pretty slick.
https://cycl.bike/collections/winglights/products/winglights360-mag
To people pointing out how not-bright these ones are, the Winglights are apparently only 48 lumens and I never thought that wasn’t bright enough. The point was to add some visibility to automobile drivers at night, not to blind them.
I like the idea of bicycle turn indicators because I often can’t safely take my hands off my handlebars to do hand signals, but 300lm isn’t bright enough. That’s $9.99 Home Depot flashlight levels of brightness.
They don’t need to light your way for you though - they just need to be visible at a reasonable distance (~20 m), which 300 lm is fine for in most conditions.
The thing is pretty nice, the price, not so much. Also the lumen is pretty low, at 300lumen highest setting per lamp you still need a high lumen for riding in darkness if you plan to see anything ahead.
I’m guessing they’re supposed to be in addition to a headlight…
I think they’re neat, make 'em cheap enough, brighter, rotatable so bar geometry is irrelevant, and move the controls somewhere ergonomic, and you’re heading towards a no-brainer. Although some 3d printer person might eat your lunch…