VAT Refund in Denmark

My friend is flying out from Denmark in a couple of weeks time and I would like her to buy a designer bag for me. I have never been to Europe and I am so confused after turning to google. Would like to see if anyone can help me with the questions below.

1. How much refund can you actually get? Online says VAT is 25% but you can only get back 10-12% max? What’s the reason?

2. I saw a website called Globalblue and you can shop tax free in Denmark, is that trustworthy? How much refund can you actually get with them? (I am sure they will take a cut).

3. What is the easiest way for her to obtain a refund? I know she won’t claim anything herself, so I don’t really want her to get to the airport a few hours before just to do the refund for me…

Hope someone can help!! Thanks!