I'm skeptical of this kind of multi-master horizontal DBMS to begin with. Never used Cockroach but have used Spanner, and even besides the $, you pay with complexity, slowness, and limitations. Even the in-betweens like Citus have their issues. As far as I can tell, the world runs on traditional DBMSes like Postgres, maybe with HA. If you're big, you run multiple and shard at the application level. I don't think there's a better option yet.

Btw, Spanner and Cockroach both have fully serializable transactions. Even single-node Postgres doesn't do that by default (though it can) because they didn't think the performance tradeoff was worthwhile. Read-committed is good enough.