I'm surprised duckdb failed to run simple count/groupby queries. Is it simply OOM? If so, do you know how much more it would take to complete those queries?
My wild guess is lack of some functions, e.g., regexp, but need to take a deep look.
It's likely out of memory issues with many many distinct values in an aggregated column, or with a very large join intermediate. The joins are now able to handle larger than RAM, and larger than RAM intermediates in a group by is on the roadmap!
Looking at the failed queries, yes, OOM might be one big factor due to aggregations (there is no join in these queries though).