Item with specificities, user can have severals items ( they create them)

Okay. Yes, I think so.
So gameplay will take place outside the App, and the App will basically just be used for logging results and calculating statistics, yes?

That’s actually the easy part. You can create a table and start adding columns with just a few clicks. But obviously there is more to it than that. You need to figure out which columns are needed and what calculations will be required. And these are things that probably only you can answer for yourself.

If you’re new to Glide, it might be worth your while taking a look at @Robert_Petitto’s Gamification Tutorial Series. This will give you a good idea about what is possible, as well as a good introduction to some Glide basics.