One of the main issues with reddit is that a lot of niche interest subreddits are 90-99% non-practitioners or extreme amateurs, even when weighted in terms of contribution. For example there is no subreddit where you can actually learn very insightful things about programming or computer science or machine learning, same for biology/physics/astronomy/etc.
I would be ok with a not-reddit competitor that actually succeeded in being a better reddit. But the #1 thing they should avoid at all costs is taking VC money. You can't have a great community of experts that is also trying to maximize it's viewership, that's how you get Quora or Reddit
It's a non-profit site created by a former Reddit admin Deimorz (known for being the creator of /u/Automoderator, /r/SubredditSimulator...).
It's currently in closed alpha so the community is somewhat exclusive because of that; but if you wanted a HN+reddit hybrid, then it might be worth checking out.
sub: /r/Tildes source: https://gitlab.com/tildes
If you really want an alternative, convince Musk to do it (or bless yours) and tweet it out. Even then I bet it would take years to match Reddit, and it may or may not ever actually exceed it.
Voat? Yeah, they're kinda gross...