Controlify uses a moderately outdated version of SDL3, Which causes in some causes some side effects, Mainly being lack of current support for the steam controller (2), Though support has been merged into the main SDL Github repo. I have confirmed its working by manually replacing the mods SDL3.dll / libsdl4j-natives with their most recent versions from github and maven respectively. Confirming this is just an issue of a supported SDL3 version not being shipped with controlify as of yet.
Update the internal version of SDL3, Controlify uses to 3.4.10 (Or current at the time), And the accompanying version of libsdl4j-natives, To match.
An alternative may be to package SDL3, But provide an (optional) way to update the SDL version packaged with the mod to provide support in existing modpacks to newly-released hardware, Even before proper implimentation can be done by you.
Below is two images:
This image is with a stock install of controlify, with an connected steam controller 2, with no instance of steam running. it does not detect it.

This image is otherwise the same, with an connected steam controller 2, with no instance of steam running. It differs due to myself having forced the mod to use a more recent version of SDL, It does in this instance detect the controller.

Controlify uses a moderately outdated version of SDL3, Which causes in some causes some side effects, Mainly being lack of current support for the steam controller (2), Though support has been merged into the main SDL Github repo. I have confirmed its working by manually replacing the mods SDL3.dll / libsdl4j-natives with their most recent versions from github and maven respectively. Confirming this is just an issue of a supported SDL3 version not being shipped with controlify as of yet.
Update the internal version of SDL3, Controlify uses to 3.4.10 (Or current at the time), And the accompanying version of libsdl4j-natives, To match.
An alternative may be to package SDL3, But provide an (optional) way to update the SDL version packaged with the mod to provide support in existing modpacks to newly-released hardware, Even before proper implimentation can be done by you.
Below is two images:
This image is with a stock install of controlify, with an connected steam controller 2, with no instance of steam running. it does not detect it.


This image is otherwise the same, with an connected steam controller 2, with no instance of steam running. It differs due to myself having forced the mod to use a more recent version of SDL, It does in this instance detect the controller.