There is some simple workaround, though:
extends Node2D
var property: Vector2:
set = set_property
func set_property(v: Vector2) -> void:
property = v
func _ready() -> void:
some_func(set_property)
print(property)
func some_func(setter: Callable):
setter.call(Vector2(0.1, 0.2))
As this uses a setter function, you can still set/get your property as before, like:
func _ready() -> void:
property = Vector2(0.5, 1.5) # "directly" setting the value
print(property)