This was one of the problems I ran into https://github.com/kysely-org/kysely/issues/664, not being able to use functions inside onDuplicateKeyUpdate

Basically no ORM supports such specific functionality of a specific DBMS. In any case you'd have to use raw SQL. I don't see the problem, this is expected.

I don't see how not using Kysely would make it better overall - you simply write the raw SQL yourself as you would without it; but you gain so much type safety by using it.