Article from 2021 says originally she was supported by her parents in Sweden, but now she is on her own. I notice she has a series on the PBS World side channel.
https://www.greenmatters.com/p/who-supports-greta-thunberg
Article says she has used funds she receives in awards to create her own foundation.
She has become a figurehead for the environmental movement. You would think environmentalists everywhere including their organizations would be supporting her. She needs to cover her living expenses but also travel and participation in environmental events.
So far looks like she has no commercial interests behind her.