The Postgrex driver works with cockroach as-is, and they're open to making tweaks as necessary (I made a small patch to Postgrex to support the way cockroachdb encoded empty arrays and it was quickly accepted).

I don't think Ecto works as-is, you'd have to check.

For simple apps, it might be a drop-in replacement, or require very few tweaks. In addition to the issues mentioned in the OP, the cockroachdb documentation has a detailed list of differences (1).

(1) https://www.cockroachlabs.com/docs/stable/detailed-sql-suppo...