Dynamic on conflict definition

I am struggling to set up the SET part of my on conflict definition dynamically.
Everything else working smoothly, but failing to pass upsert information.
Would welcome any help.

const targetTable = "test"
const columns = ["id", "name", "geometry"]
const onConflict = { keys: ["id"], update: ["name", "geometry"]}

await sql`
  INSERT INTO ${sql(targetTable)} ${sql(data, columns)}
  ON CONFLICT (${sql(onConflict.keys.join(","))}) DO UPDATE
  SET ${sql(onConflict.update.map(column => `${column} = EXCLUDED.${column}`).join(",")};
`

Start by reproducing the provided JavaScript SQL template against PostgreSQL and inspect how the client handles dynamic values in the ON CONFLICT SET expression. Compare the behavior with the documented interpolation rules; done means the dynamic upsert information works as intended or the limitation is clearly documented.