Theoretically, any could do so but would always be at the mercy of great powers (France and Britain).
Belgium was allowed to do this as they were not a threat to anyone and maintained good relations with either country. They were not interested at all in involving themselves in local wars either.
If Germany, Spain, Austria, Denmark, or some other power that was involved in the wars of the 1850's through 1880's, one would think the chance of France or Spain intervening to be more likely.
Any ideas if the Ottoman could potentially colonize something like this?
Like most European powers, they may simply want the status symbol of being a real power, despite that influence rapidly fading.