The problem apps are shutting down is because they don't want to loose money. If they make a new site, they will likely loose even more money. And they likely can't get profitable without resorting to same scummy behaviour as reddit.
Given the quotes I heard, I'd be very surprised if you lost more money in say, 2 years of building and hosting a new site than trying to even support a month of API calls from reddit c. July 2023.
You can certainly make a decent front end for little cost (even if we're talking about paying competitive rates to a few talented mobile devs) and a small backend won't cost much more. It's always about the community to gather to make all that work. That's the hard part.