I work on Paraxial.io, it’s an anti-bot tool (similar to reCaptcha or Cloudflare in function), made for Elixir, and written in Elixir.
Since you have a login page, https://goblinapp.com/users/login, you may run into bots taking public dumps of username/password pairs, then running thousands of login attempts against your site. You can use Paraxial.io to block this attack.
Hi! 
I’m building Macro, it’s a simple project management tool designed to minimise the number of meetings you need. It has some overlap with Goblin and Slab, but perhaps is closest to Basecamp in the feature set, with:
It’s all Elixir/Phoenix with a (mostly) static frontend.
You could absolutely use it to manage your startup projects and todos (I use for that everyday). E.g. Here’s a project I have:
https://macroapp.io/project/159
How could I have missed this one. Of course I use LiveBook too, probably my most used Elixir/Phoenix app 
I have my eye on a Wireguard solution which is made with Elixir:
https://github.com/firezone/firezone
I am not at a stage where I can start experimenting with wireguard, but I would like it to be via GUI than CLI.
Also this uses kernel wireguard not user space one like others.
SavvyCal (https://savvycal.com/) is imo the best Calendly competitor out there, and is backed by Elixir running on Fly.io. I think it makes heavy use of LiveView as well.