It would be really cool to load duckdb files too. sql.js-httpvfs seems convenient because it works on everything in database so you don't have to create indexes, or setup keys and constraints in the client.
DuckDB-Wasm uses a traditional buffer manager and evicts pages using a combination of FIFO + LRU (to distinguish sequential scans from hot pages like the Parquet metadata).
The blog post contains a few examples how this can be used, for example, to partially query Parquet files over the network.
E.g. just visit shell.duckdb.org and enter:
select * from 'https://shell.duckdb.org/data/tpch/0_01/parquet/orders.parqu...' limit 10;