Although major use case of Distrobox would be for leveraging application on container from host, I thought it may work for language input. If it works, it will be rational solution for language input with missing input method without binary build.
Example, Clear Linux has input framework as IBus, but no Japanese input method as Mozc. Hosting simple Ubuntu container including Mozc packages with Distrobox, then Input Sources in Settings on Clear Linux can see Mozc on Ubuntu. Then, Japanese input with Mozc works on Clear Linux works as if it is locally installed.
And put single line command at the end of .profile, it is available just after login every time.
Here is its how-to.