Me too! I think the spatial capabilities are going to advance a lot but the good news is that you can keep some data in PostGIS and mix it with DuckDB since they have some Postgres connectivity too!
Does this support indexing? Not just your usual spatial index like GIST(geom) but indexes on custom expressions? Also- great that the native geom types are fast. But do they handle change of CRS, proj, geog vs geom etc? AKA what if you need high accuracy distance calc