Derma roller Suggestions

I recently lost quite a huge share of my hair in the lockdown (don't know what triggered it) and my scalp has become very visible. I have started using 5% min 0.1% fin topical solution.

I wanted to add derma roller to my routine as I heard it gives good results.

What needle size should I start with/what gives best results? Any suggestion for a good derma roller (available in India)? I ordered a generic one from Amazon with 1mm needles. Would this suffice?

Also any guides on how to use a derma roller?

Thanks for your help!