https://www.kickstarter.com/blog/kickstarter-is-not-a-store
https://www.kickstarter.com/rules?ref=global-footer
So, within the rules: it is 'an obligation-free playground for tinkerers' more than it is a place where you can buy cool stuff that doesn't exist yet.
And in this particular case it worked exactly as it should. Obviously there are some Kickstarters that are fraudulent, where the initiator has no intention up front to ever release what they say they intend to build. But those are indistinguishable from your typical other failed Kickstarter, the one where the ability or funds did not reach far enough to stretch to the point where something tangible got delivered.
If you want to be 100% sure you get what you back: don't use Kickstarter, you will almost certainly be disappointed. If you want to back people that have the intention of doing interesting things with low expectations of actually receiving that which you back Kickstarter is fine.
A very strict reading of the rules means that Kickstarter can be exactly that: an obligation-free playground for tinkerers, who may at some point deliver something back to you in return for the money you give them. Your 'backing' is essentially a donation, there is a pinky promise that the recipient will try to do what they can to deliver on their intentions.
Some projects are more up-front about this than others, but in general it helps to understand the kind of arrangement you are entering into before deciding to back any kind of project.
This is the project page for this watch:
https://www.kickstarter.com/projects/920064946/oscilloscope-...
The timetable seems - to the hardware oriented part of my brain - wildly optimistic. Otoh 10 years is probably much longer than the original project was intended to run, likely there were serious troubles sourcing parts and/or with the final design. But the person behind the project felt that in spite of that headwind they still were obliged to deliver, even if that happened much, much later than intended. I wished all Kickstarters would end as happy as this one.
https://help.kickstarter.com/hc/en-us/articles/115005048113-...
So: other than a 'gentle-mans agreement' you do not have much to go on in terms of rights. Finally: the amount of money raised for this project is so low that I'm surprised it managed to run to completion at all.