Just to expand on this - ElectricSQL and PowerSync (and some others like Evolu) use a simple but quite effective approach to get reactive queries:

1. Listen for updates to the table(s) used by the query, using SQLite's update hook or similar approach.

2. When a table has changed, rerun the query.

There is no incremental updating of row results, no smart detection of whether the updated rows have an effect on the query. But it works with practically any query, including joins, aggregates, and even views and CTEs in the case of PowerSync and Evolu. And in most cases, SQLite is fast enough that performance is not an issue.