Currently Parquet is supported as external table, but one cannot specify make_valid, planar or oriented option. So only Parquet files with valid spherical geometries are supported, if you want such a column to be presented as Geography type in external table.

On the other hand, you can define such a Parquet file as external table with geometry column as String column, and use ST_GeogFromText with options in each query using it. If this is inconvinient, I would probably build a view on top of this that presents this column as Geography type, again using ST_GeogFromText with appropriate options.