Alias doesn't show up in subtypes

I am attempting to make a function that compiles a list of all the subtypes of an abstract type defined in my module, including the names of all the aliases defined within my module, and from outside the module.

module A; 
    using InteractiveUtils
    abstract type Thing end
    function list_all_things()
        return subtypes(Thing)
    export list_all_things
struct Thing1 <: A.Thing end
struct Thing2{T} <: A.Thing end
const Thing3 = Thing2{3}
# 2-element Vector{Any}:
#  Thing1
#  Thing2

Is it possible for the above list_all_things function to also return Thing3? I thought of using names(A), but that won’t work because I need to be able to define the aliases outside the module.