Pipelines for different processing steps

[scidam]

Can we have a pre-step on the filtering and data scaling?

Yes, we can! If you look at the example, it includes StandardScaler as a step in the pipeline. StandardScaler has its own set of kwargs, e.g. with_mean, with_std.
So, you can organize pgrid

pgrid = {
'scaler__with_mean': [True, False],
'svc__C':  [1, 10], 
}

and use all of this in GridSearchCV. Thus, data scaling step is incorporated into one model.
Finally, GridSearchCV allows to find best combination of parameters that influence not only
classification step, but preprocessing (scaling) too. Nothing prevents you to do the same thing for data filtering. Define FilterData class (you can use the source code of StandardScaler as example) and incorporate it into a pipeline.