i am just a 'noob' in crypto , and beginning to learn more about it ;
i just wonder, when 'common people' (like me)
can pay with 'fins' in a shop , bakery, pub, etc..... ?

It is easy.
1. Convert all your "fins" in bitcoins.
2. Sell your bitcoins to me.
3. You now have fiat currency and can pay in a shop, bakery, pub etc.