Pictured here is the ones by Velorian for E-Bikes
Bicycle indicators are available to purchase and there's some variety going from gadget that breaks in a day to proper ones. But there is surprisingly little of them and most of them run on batteries and standard bluetooth connections which I think is kind of ass for something safety critical.
Anyways germany, in 2024, finally made bicycle indicators legal for all types of bicycles instead of only 2 tracked ones or where the way it's built would make it impossible to use your hands and people have gotten cracking at building something, to me, better.
This one hooks up to the E-bike battery, which at least in germany will keep on the lights even if empty on reserve power because LEDs don't take much. They also build one with a dedicated battery pack and wired everything you can hook up to your dynamo to recharge as you ride which imo takes a lot of hassle out of it.
Everything is of course made to esoteric german safety specs and as such the pre-order model costs about 200 - 250€ all said and done. But I'm guessing in a decade these will have arrived at a more reasonable price.
I think given sufficient infrastructure this is a bit of a non issue or otherwised solved by putting 2 eurodollar glowing slap bracelets on your arm, I find it fascinating mostly because I love bicycle gadgets.
Having said that: I think there's quite a few cases with people with disabilities this'd be hella useful for or even just open up bicycle transportation at all and for beginners, if costs go down, this could also be good. I mean riding one handed is a skill distinct from being able to ride a bicycle.
Positioning needs some work though imo, I've seen a lot of "mounted next to the rear brake light" solutions and it feels kind of too tiny as per distance. I think maybe some sort of Fisher 360° light approach'd work better, i.e. projects downwards also:
This does have the problem of being still hard to see out of your angstpanzer 4.0 at any distance less than 20m, but I don't think you can engineer yourself out of that one without touching the angstpanzer 4.0
also looks like Need for Bicycles: Underground 2 as a bonus tbh
Oh yeah I definitely gonna need to get an underglow kit and mount a fat sub to my cargo rack