There's a few kinds of limitations:

a) companies hiring only employees - usually only hiring in a set list of countries, because direct employees in places you have no presence are a pain. Hiring contractors puts the burden of a lot of that on the worker, so companies are more flexible.

b) companies hiring only in specific timezones - usually with the expectation that an entire team has basically the same business hours. But e.g. an US company with such a rule might very well take contractors from South American countries too, or an EU one from Africa). Without knowing further where exactly you are, that might be worth looking for as a signal (and if they mention time zones and you aren't quite in it, explicitly mention that you understand the requirement and are able to adjust appropriately when applying. Fundamentally these companies usually do not care that you actually live in those places, but they do expect you to match their work times)