Derivation for semiauto typeclass not possible

[sake92]

I have a semiauto typeclass, i.e. using def derived, and not given derived.
Is it possible to derive union typeclass for a semiauto typeclass?

Repro:
https://scastie.scala-lang.org/CYcSgAxZQCGoOY4VdsOXew

Btw your lib is really nice and useful, great job! :)