[Shinmon]

DevOps is more a philosophy than a specific role.

Nowadays, there are a lot of positions that are devops engineers, but that's mostly sysadmin-like work but automating a lot by configuring systems through yaml instead of directly working on said machines.

Of course, there are also people who develop internal tooling, and platforms enabling the developers to simply create test environment themselves. The real problem here is that every company has their own version of what they think that is ;)

Backend developers might work on this a little bit, depending on the company but usually providing the infrastructure is usually not they main responsibility.