The ISS is completely self-sufficient for water and air. No country on Earth is fully self-sufficient in what it uses and is dependent on supplies shipped to it from elsewhere.

The word colony in the sense of space exploration and other extreme habitats means permanent occupation and exploitation of the resources there.

Doesn't ISS generate oxygen from water and water is essentially shipped in? Either as water or as food. In the end methane is vented to space. I wouldn't call system needing pretty major inputs a self-sufficient one.

You are correct:

>4. Sabatier reactor

>Inside this machine, a blast of roughly 750°F heat breaks the bonds inside CO₂, forcing it into its constituent elements. The carbon and oxygen combine with hydrogen from the station’s ­oxygen ­generating system to make H₂O and methane (CH₄), the latter of which vents into space.

https://www.popsci.com/how-iss-recycles-air-and-water/

Every last molecule used on ISS is boosted from Earth, and recently. ISS does a bit of recycling to reduce the amount needed. There are exactly zero permanent inhabitants: any would die. They exploit no in-situ resource, except sunshine using frequently-replaced solar panels.