Servus Mateusz,

this shop sells and repairs coffee_machines (fully automatic coffee machines, portafilter machines, percolators), mainly for private use.It is similar to shop=vacuum_cleaner, only for coffee machines and associated products.
In my opinion the best tag would be "shop=coffemaker", but I changed then to coffee_machines because the number was 10 times higher.
I didn't find then or today any tag in shop to subtag "coffee_machine=only/yes".

Servus thobrist