The specific operation process of the dpgen init_surf command

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I only found the tutorial about dpgen init_bulk. There are no tutorials about dpgen init_surf available online at present.The question I want to ask is:

1. I want to create an initial dataset on the surface reconstruction of BiVO4 crystals through dpgen init_surf. How should I set the parameters of INCAR_relx and what are the differences from the parameter Settings of dpgen init_bulk?

2. I only want to obtain a small number of configurations because I'm currently in the beginner stage. I want to run an entire process with a small number of structures first. How should I set the parameters when running the dpgen init_surf, param.json file? Previously, I modified the parameter "coll_ndata", but still generated at least 1500 structures for structural optimization.Here I attach my param.json file and the parameters of INCAR_rlx.Thank you for reading my question carefully. I hope you can answer it
   param.json