Its great to see scale and progress, but being closed source is HUGE DEALBREAKER.
Clickhouse is also on the right track of building some amazing opensource integrations with postgres, they have superior*[1] managed postgres looks like from their recent blog. I hope they do some OSS sharded postgres solution.
[1] - https://clickhouse.com/blog/benchmarking-nvme-managed-postgr...
If you want an OSS sharded Postgres, just use Citus. Feature-full, proven, mature, boring.
Sai from ClickHouse here, I lead the Postgres efforts at ClickHouse. Expect news from us on this soon! Many of us here are ex-Citus and have done this for Postgres before.