I've looked at Gleam before but it didn't seem to have any mechanism for dynamic dispatch like interfaces or type classes. Did it change in the meantime?
Elixir does have protocols, but they are extremely limited compared to type classes, traits, etc, and they're uncommonly used compared to writing concrete code.
Both of type classes and interfaces desugar to high order functions, so anything you write with them can be written with first class functions, though with a less concise API.
Of course dynamic dispatch can be implemented in almost every language. The Linux kernel uses dynamic dispatch with C!
But that's a hack, not a language feature.
PHP has interfaces and whatnot, but a lot of the time I do polymorphism by just having a class that has Closure members. When you can arbitrarily pass around functions like that, it's basically equivalent to an interface or abstract class, with a bit more flexibility.