Supertype of all geometries

[Sov-trotter]

What is a possible supertype of all geometries in GeometryBasics. I mean for a function where we are expecting GeometryBasics geometries(I want to multiple dispatch that function for GB geometries and some other structs too).
Also,

julia> using GeometryBasics

julia> Point isa UnionAll
true

julia> Point(1, 2) isa UnionAll
false

[Sov-trotter]

julia> Polygon([Point(1,2), Point(5,6)]) isa GB.AbstractGeometry
true

julia> Point(1, 2) isa GeometryBasics.AbstractGeometry
false