not much to tell beyond the picture. Some of them are hand cranked, others include e-motors with throttle either because there's legal modes for it or maybe you're at a bikepark where usual public regs against that don't apply.
Mostly niche-builds, so custom things adapted to specific customers or small scale lines
There's a channel about building various iterations of these adaptive e-trikes: https://www.youtube.com/@bdcainathotmail
Loads of cool concepts like mounting a solar panel roof, full independent suspension and most of the construction is just simple tubes and stems much like an "erector set".