I'm wondering how HoneySQL could support OVERRIDING SYSTEM VALUE for inserts on columns that were created with GENERATED ALWAYS. I believe it's part of the SQL standard, although I don't have access to the spec. But https://www.postgresql.org/docs/current/sql-insert.html, at least.
Please create a GH issue with a link to the (PG) docs and I'll take a look when I'm next working on HoneySQL.