I mention RDS because it mostly solves the failover/continuity problem. While failovers on RDS are typically outages, they're also typically quite short lived, no more than a few minutes. That can work for many people/business's requirements. That it is managed means you (in theory) can rely on AWS to manage the underlying infrastructure. You just worry about the SQL. It is a "boring technology" choice, as the article that HN likes to post every now and then says.
Litestream: What are the durability guarantees? (Are there any?) what would make me pick that over RDS or Cockroach? "given that SQLite is just a file, it’s incredibly easy to replicate" — sorry, that just doesn't click with me. What about a file is "inherently easy to replicate"? I would not know how to implement something that wouldn't be O(n) with the filesize. Ideally you'd just sync up changes, but how to get those? Normal DBs with streaming WALs (RDS/PG/MySQL) or Raft-based replication (Cockroach) have good answers there.
Expensify: I skimmed the article, but AFAICT, the article talks about scaling QPS to a single SQLite file, but nothing about replication/durability.