As an engineer who's spent a good chunk of his career working on stuff that got cancelled, it's really not that bad. You're generally paid well and looked after, learn a tonne on someone else's dime, have good job prospects, a strong network of talented colleagues, plus most engineers are there for the team problem solving and challenge anyway. The final product release is just the cherry on top.

After all the layoffs in the tech sector, it's doubtful it were even the original engineers working on the project.

It’s kinda part of the job. Several times in my career I’ve put in months of effort on projects that then get canned for various reasons. One of them was 100% complete. No real big deal, it’s still a good billet on my resume.