> The combination of SQLite (libsql, a concurrent implementation of sqlite) and Rust means I can do so from a $2/m VPS and a single server instance.

You can probably do it with regular SQLite, too. Being limited to a single writer isn't as devastating as it sounds when they get processed very quickly. Probably don't need Rust either but it'll be more efficient than the usual choices.

(Also, it looks like libsql is the same as SQLite? Only Turso has concurrent writes)