This agent honestly needs some changes, right now neon can't replace any of the actually viable duelists like jett and reyna (sometimes raze as well). Some changes could be:
Make her speed buff a passive, being able to go 30 percent faster is not really that useful especially if she can't have her gun out. There shouldn't be a limited amount of time for the speed buff and she should be able to keep her gun out like normal, and of course the bullet inaccuracy would increase even more with the extra speed as well. If that becomes a bit to oppressive, then only give her the 30 percent speed buff while she's using her ult and lower the passive to around 15 percent.
The slide ability should be a little bit more like jett's dash, while still having a few key differences to differentiate the agents' identities. Something I would like to see is the slide being being the slightly faster in the beginning and it being able to go in more directions, if not backwards, at least left and right. The slide can stay the same speed as it is including the time it takes to pull out your gun again, right before the slide ends, but the very beginning of the slide needs to be around the speed of jett's dash. This would add another duelist which is viable for oping as she slide could act as a dash. The abilities would be different enough because neon's slide is slower overall but she gets her gun back faster.
The ultimate is mostly balanced but i would say maybe buff its damage a bit but make it have a huge distance fall-off as well, as for the ult while jumping, it can stay as it is or increase the accuracy. This would make her ult just a bit better while not being overpowered and more competitive with jett's ult.
Other than that I think that the double wall and stun are good abilities. The stun is currently the best part of her kit and the wall is not the best but pairs very well with the rest of her kit. When taking or retaking a site, the isolated lane created by the wall can allow her and her teammates to position themselves and use util from within the lane before taking over the site.
Thoughts?