My understanding is we do sponsor H1s. The vast majority of nationalities are fine, however we do have on-premises computing on a Department of Energy facility, and they bar citizens of the following countries from being granted an account on their systems: https://www.state.gov/state-sponsors-of-terrorism/ so a candidate with those nationalities would be at a disadvantage.
Unfortunately for reasons outside our control, remote work is only possible from residents of the following US states:
Arizona
California
Colorado
Florida
Hawaii
Maryland
New Mexico
Texas
Virginia
Washington
Washington DC
I think, I'll throw my hat in the ring.