It's not that bad, I'm on my second Elixir job in 3 years and in Asia which is even harder to find.
There are a good amount of jobs in the US or in Europe but you have to actively look for them...
I can however say that working with Elixir has been really pleasant and even enjoyable, and I'm not someone who codes outside of work. I'd definitely recommend it!
Whether it's a good idea or not really depends on your app, what you're trying to do, and who your users are.
Now if you want to avoid round trips to the server for interactions such as opening a modal, you can!
There are at least two ways to handle this - Javascript hooks that let you attach JS to your DOM, or the light AlpineJS framework. The latter is a perfect fit for Liveview and it's part of the unofficial go-to stack name PETAL - Phoenix Elixir Tailwind AlpineJS Liveview.
This has most likely to do with the codebase itself rather than with Elixir or Phoenix in your case.
And having to go through a few files to understand how a request is handled is not out of the ordinary in an app, especially if it's grown over the years?
I just switched from a Python (with mypy) codebase to a full-time Elixir position a few weeks ago.
I thought I'd miss typing but due to the functional nature of Elixir and its pattern-matching, I found out that the code is much simpler to grok.
In this case I think that having readable idiomatic code trumps the need for typing.
If needed there is type hinting with @spec but it's not used very often (or mostly in libraries?).
I can definitely say that it's very fun and productive to work in a Phoenix mono-repo. The development experience is great and I'm really having fun programming again.
There are a good amount of jobs in the US or in Europe but you have to actively look for them...
I can however say that working with Elixir has been really pleasant and even enjoyable, and I'm not someone who codes outside of work. I'd definitely recommend it!