📚 What distributions are used the most professionally? (IT, Sys Admin, Workstations, Embedded Solutions, Special purpose machines, etc)

I'm wondering what linux distributions see the most use professionally. It seems like RHEL dominates sysadmin roles largely because their certifications makes it easier for employers to find employees who are ready to work on RHEL specifically but beyond that it's not very clear. I read that NASA uses Debian which I would consider that a special purpose machine doing whatever NASA engineered it to do. Workstations can vary between numerous individuals who do freelance work on their own to businesses that might mass deploy a certain distro. Embedded solutions could be anything.

I'm trying to get a picture of this in 2020 right now and what direction things might go with the recent advances in ARM architecture.