Tebako seems like the most promising option currently working on finding the way to package a rails app into an offline app. This article seems to show that it is very much possible using tebako and they even added in a specific host folder mounting feature to allow rails to work with its use of absolute paths.

I do think tebako is not all you need because it packages it into an exe but this is the same as just running a rails server on your computer. You still need to use a browser window to load the app and make requests so it would require another library to run the browser and this exe and then make requests to the servers url. I'm pretty sure there are apps that work like this quite often. I've seen ones where you click on the app icon and it opens up the browser to view the app. So I wonder if that is a similar example.

https://www.tebako.org/blog/2024-10-18-tebako-mount-and-ror/