So, know that when applying to this large set of universities, and paying a huge amount in fees, you need to plan for 4 years of education only, and then returning to your country.
The universities here will educate you. You are considered a guest of the university and the US government. They are under no obligation to provide you with any sponsorship for employment or living in the US. That’s under the control of US immigration policies.
Additionally the US government requires employers to seek out American citizens and permanent residents first, for any open positions in their companies. As a non-resident, even with an OPT year, a company is not required to employ you in the US. Priority goes to citizens and permanent residents.
Environmental studies and public policy is not lacking for applicants/graduates who wish to become employed in this area.