Custom credential type plugin

Hello
Can anyone point me to the documentation piece how to create custom credential type plugin?
For previous versions there was ability to install the plugins like documented here:
https://github.com/ansible/awx-custom-credential-plugin-example

But if I understand correctly latest images are rootless and also awx-python is no longer available.
Closes I managed to find is here:
https://docs.ansible.com/ansible-tower/latest/html/userguide/credential_types.html#getting-started-with-credential-types

But it is more fore static credentials.

And here: https://github.com/ansible/awx/blob/eec4f8dcc27428cd1aeb1c251d43052a3ea780e8/docs/credentials/credential_plugins.md
But this one points to the same example, which is created 2 years ago

Hello,

Since you’re installing the plugin with pip to the awx environment, you most likely need to create a new awx container image that includes this pip installed dependency. If you create a new container image, you’d then need to configure the installer to use the image when deploying. There’s a section in the awx-operator docs that discusses how to use a custom container image, which will probably be helpful for this: https://github.com/ansible/awx-operator#advanced-configuration