It's surprising that no one has thought of it first.

I could see this being useful. Not everyone who uses a wheel chair is paralyzed. Some have balance issues, or limited strength. Dividing the effort between arms and legs could give increased independence and it would be more ergonomic than scooting with the feet like a lot of people end up doing in wheel chairs.
Sure, it's not super different from a recumbent bike (and seems to lack a steering mechanism) but if the pedals could be folded out of the way it could be easier for a person with mobility issues to get in and out of.
- It's not necessarily about usefulness but rather quantity and economics of scale.
  The number of people needing wheelchairs in the first place is pretty small compared to the population, and adding the additional caveat of those that can still use their legs fully to power what is effectively a bicycle, results in a venn diagram with an extremely tiny use case.
  The cost of a decent basic wheelchair (not AliExpress/Walmart shit) is already high. Adding the complexity of a bicycle on top of that just makes it more expensive. And then there's insurance which almost certainly would tell you to kick rocks before they would even think of covering a fraction of the cost because it isn't necessary.
  
  This is literally why those silly "as seen on TV" product commercials makes sense. You know, the ones where ordinary looking people seem super, incompetently incapable of doing normal everyday tasks. The snuggie sure seems stupid... Until you realize it it's meant for people who are disabled with mobility issues. Then it makes complete fucking sense. Most of those things were designed for disabled people, but that's a really small market to appeal to, so they broadened their market in order to make the things affordable to the actual target demographic.
- Maybe this is a picture of some real hospital equipment? I didn't check for pixels.
  
  It looks real, the top left poster reads "bone decalcification". However it seems that it's only for braking.
- I think wheelchairs with a gear system and electric propulsion
  
  You just increased the price by at least 100x for only double the production cost.

I once suggested a similar project at our company. One of our products is labelled in braille. For technical reasons it was the easiest way to drill holes in the front plate and stick a transparent plastic insert through from the back.
My suggestion was to add a few blue LEDs behind it to light up those braille dots. It would have been meaningless for the intended user - but it would have looked way cool!
- I often think of this sign I saw at a small children's playground with braille on it hung 6 feet in the air with no way to reach it.
  
  I think of the sign that says "hot surface do not touch" with accompanying braille.
  
  There's also no way for someone who needs Braille to actually DO the "puzzle". The other words don't have Braille, the map appears to be flat. Terrible design.
  
  Surely they could have made that a little more challenging than having a straight line?
  
  Maybe the builder just mounted the panel the wrong way? It serves as a wall for the platform behind it.
- I'd like to think of that as supplementary design.

They exist, but the pedals are higher, for your arms! I used to work with a guy who did this: every day at lunchtime he’d go zooming around the parking lot getting a good workout in
https://bike-on.com/product-category/shop-handcycles/attachable-handcycles/
- I'm an able-bodied handcyclist. Not a wheelchair attachment, but a dedicated handcycle. I've been riding one for over 20 years now. I alternate riding it and riding a leg-powered bicycle. Cycling and hiking are the only exercises I will religiously stick to. I realized that my upper body was being neglected and gave a handcycle a shot.
  They are super fun and a great workout. I prefer my handcycle rides tremendously over my to eg-poweted bicycle rides (but I can't skip leg day). I highly recommend trying out a handcycle to anybody who thinks they may be interested.
  If you're in the Los Angeles area, and are interested in trying one out, message me. I love introducing folks to handcycles and live down the block from a bike path. I even have a couple for sale that I'd let go at a very reasonable price if anyone wants one. I just don't want to ship them.
  
  This better not be like the last time someone on the Internet invited me to come visit them in a strange city if I was curious about trying hand stuff.
  
  I’m definitely curious, but opposite coast
- took scrolling to this comment before I understood OPs joke.

I mean, there are people who need a wheelchair but are still able to use this.

It took me longer then i want to admit to realise why this is a bad idea

Honestly, this might be good for use as a therapy device for people that perhaps have weak arms and legs and perhaps cannot stand up. Dividing the work required in this way has some merit to at least be studied or researched, if it hasn't already.

Gotta have a 100 bad ideas before you discover a good one.
Like what if you added hand pedals?
- Like what if you added hand pedals?
  You'd be late, already exists.

They is surely people whose handicap allow to use their legs but not to stand up. Come to think of it, I know some people who are this way.
- Even assuming use of your legs, you can't steer this
  
  It's a project. It might not be finished yet.

I have this meme in my roll and I've been scared to post it lmao
- Worried about people's reaction?
  I frequently save memes in my ever-growing folder, then skip them at the last moment because I worry the audience here might think it's over the line. This one seems to have landed though.
  
  Could be a good barometer.
  Maybe slightly spicy to those close to wheelchair users, maybe - but doesn’t punch down at all, just good natured fun.

I was like: wow this is actually genious... oh.

Recumbent bikes are a thing. That is basically this

You need to cover the chain for safety during operation.
You need foot straps and side leg protectors/support.
Could this possibly exercise leg and foot muscles of people with no lower mobility due to spinal/nerve injuries?

To qualify for a wheelchair under American insurance, you have to be unsafe to use a walker or cane for mobility, be primarily wheelchair bound (need person to help transfer you or have enough upper body to transfer yourself), etc. Most patients I think of that I discharge with a wheelchair would not be able to use this device...
For those that can use something like this, there are so many micro mobility things out there. As someone pointed out recumbent bicycles already exist.

Wall-E?