Update 5/3/2021: Rails experimental support is currently broken. Instead of investing time to fixing this experiment, will consider leveraging container image support which is a better approach.
Jets supports deploying Rails applications with a few approaches that are experimental.
Mount Rails App?
Rails is also rack compatible, so you may wonder if you can mount a Rails app with Jets routes mount support. Mounting a Rails app is not currently recommended. Some thoughts on this here: Mounting Rails Apps