Is there a way to get wp_editor (tinymce) content?

I can’t comment yet… so I will use an answer, I think you need to do it with ‘wp_insert_post_data’ filter.

You can see this in line 3523 here: https://developer.wordpress.org/reference/functions/wp_insert_post/

Your function need to have a parameter, which is an array. From there you should get the content from ‘post_content’ key.

add_filter( 'wp_insert_post_data', 'example' );
function example( $data ){
    $post_content = $data['post_content'];
    // ... do your stuff
    $data['post_content'] = $post_content;
    return $data
}

Note: this will not get the tinymce content, This will get the data right before it’s introduced in database. You should also take some attention at shortcodes, I don’t think that you can modify the content in shortcodes via that filter.
Hope it helps you, or someone else.