Mastodon’s “Explore” section does a good job of aggregating the “Trending” [whatever that means without a real algorithm] posts from all the servers that federate your instance, so the kind of front page experience you’re describing is definitely within the realm of possibility. Someone would just have to build it.
I think it’s important to keep in mind that this is all in “minimum viable product” territory, rather than being the final form Lemmy/Kbin/etc. It’s really exciting to think about all the new and weird features that are possible, assuming people put in the time to develop them, and users provide support, either financial or other.
I’ve been a Kagi user since launch, and it has completely replaced everything for me except image searches. It’s the best $10 I spend each month.