A bunch of companies are selling laser lane markers (perhaps rebranding a gadget being pumped out of a factory somewhere on the outskirts of Shenzhen). These are rear lights for bicycles that incorporate downward-sloping red lasers that create lines on the road behind the bike.
This is for some reason expected to be safer than a blinking red light on its own.
These are available online for $25 or less. I’ve never seen one in the wild.
I’ve seen one when riding… and I kind of like it. It is an attempt to mark your space and advise drivers not get so close to you. It is another attempt to be seen, and that can’t be too bad.