Yes I have seen them, but they are all written in YAML which I don’t like.
So I have made one in python as a costum_component, but it requires some input_boolean defined in YAML and I’d really prefer to have them initalized by the python script.
But it turns out that HA has some abstract classes, if you use them, then an input_boolean (or whatever you need) appears.
I’m not that familiar with the python abstract classes, so I have not been able to figure it out 100%, but here is a video where the dev of HA explains it.