how to pass data from one action to another, with a form in between?

Question

I found here a way to do a direct passing of data (magento 1) but what if the first controller serves a BO form and then the other controller gets the data, kinda like edit and save of customer module.

I'm currently trying this approche:

1. overriding \Magento\Customer\Model\Customer\DataProvider
2. modifying meta of said form $this->meta = $this->modifyMeta($this->meta);

3. in modifyMeta() do this:

   //adding my field to be processed in the save controller (BO)
   $meta['customer']['children']['my_field']['arguments']['data']['config'] = [
       'formElement'   => 'input',
       'componentType' => 'field',
       'visible'       => '0',
       'value'         => 'my value'
   ];
   

But in the processing controller, the param is not retrieved with $this->getRequest()->getParam('my_field') (I get a big fat NULL)

if there's maybe a better way, please advise.