I understand that MySQL follows a specific pluggable storage architecture. I also understand that the direct equivalent in PG appears to be table access methods (TAM). However, you don't need to use TAM to build this - I'd argue FDWs are much more suitable.
Also, I think this design assumes that you'd swap PG's storage engine and replicate data to DuckDB through logical replication. The explanation then notes deficiencies in PG's logical replication.
I don't think this is the only possible design. pg_lake provides a solid open source implementation on how else you could build this solution, if you're familiar with PG: https://github.com/Snowflake-Labs/pg_lake
All up, I feel this explanation is written from a MySQL-first perspective. "We built this valuable solution for MySQL. We're very familiar with MySQL's internals and we don't think those internals hold for PostgreSQL."
I agree with the solution's value and how it integrates with MySQL. I just think someone knowledgeable about PostgreSQL would have built things in a different way.
Anyone using it in prod even with the beta status?