That's not supported yet, but it will involve removing the foreign key constraint from one table (by parsing and rewriting the CREATE statement before running it). Then after the referenced table has been created, add the FK constraint with an ALTER statement.

There's also the DEFERRABLE constraint setting[1] for one-to-one relationships (which can usually be avoided via a joint reference table). This pattern should already work in pg-nano.

[1]: https://www.postgresql.org/docs/current/sql-set-constraints....