Elixir seems so magical. But it also seems really difficult to use in a project because you will never be able to hire someone that knows it.
It's not that hard to learn. Once upon a time very little number of people knew Ruby too. Elixir became mature and production ready extremely quickly compared to other languages I've seen. The advantage it offers is also massive, it solves a real problem and does it very well. So I wouldn't let the ability to hire someone be the reason. Any forward thinking venture knows that. The documentation is great the community is great, elixir is ripe for the curious to get started learning and being productive quickly. You just have to want to learn it.