I've hit a bit of a wall. I wanted to build a graph-backed asset that loads a DBT-generated database table into memory and then saves it as parquet/csv. I would like it to be graph-backed so I can reuse it. But to build a downstream dependency I need to control the IO manager and I cannot find any examples of how this can be done with graph-backed assets?

For the particular outputs that map to your asset keys for your graph-backed asset, specify the io manager key that you want to use for persisting that asset (in this case the IO manager that saves as parquet/csv) and then in your downstream asset, you would use the same io manager to load.