Several fintech companies use it to power core logic, with or without phoenix, so it's used for general purpose computing where speed, resiliency, and parallel execution are important. I've seen hints that people are using it to run crypto trading bots, but idk how common that really is.

I think a few companies use Elixir to power their web crawling/scraping tools. This makes intuitive sense as a good candidate for the process supervisor and parallel work architecture OTP encourages.

Nerves (embeddable Elixir) has come a long way. I switched to Nerves for some Raspberry Pi projects and the amount of time I waste dealing with hardware/config has gone to nearly zero. I am a hardware novice and was able to setup flashing firmware over-the-air updates to the Pi with very little effort. I'm sure the companies that use Nerves in production have more to say about it.

I'm not very tuned into the updates to Scenic, a project for display/UI on embedded screens, but it looks like they've hit some big release/stability milestones.

Phoenix is the way to go for web interfaces, and is an excellent toolset, so alternatives haven't been demanded. For more lightweight http people usually reach for Plug, a key building block of Phoenix, if you won't need the full bird.