I tend to use env variables instead of env files (12 Factor Apps - https://12factor.net/). Safer, not safest. As @late_night_fix mentioned, there has to be a balance.
If you don't mind my asking, how much setup did you have to do on the remote runners? And/or how much time do you find you have to spend on ongoing maintenance on those runners? Have they been fire-and-forget other than occasionally doing a `docker pull` to update them, or have you needed to fiddle with them every other week?
The main point of hypermedia is the browser, not a gaming platform. Not even the mobile platform. HTMX is not purposed nor it advertises that it should be used outside of the browser scope.
I use Unpoly that replies on the same principles (HTML over the wire) and both of them are very clear about their intentions.
In my mind collaborative apps are a core feature of the web. Streaming hypermedia is a great way to keep all your state on the server and have a solid multiplayer/realtime experience, especially with large datasets.
Here's a basic google sheets clone that does just that: