The drops can be given in a small amount of milk on a teaspoon. However, these products should not be diluted in the entire volume of milk, i.e. in the entire bottle. A probiotic or Espumisan could settle at the bottom of the bottle and the child would not take the entire dose of the product, so it is better to administer it on a tiny spoon.

Here you can compare the prices of these products in online pharmacies and place your order with home delivery or pharmacy pickup:

https://www.gdziepolek.pl/produkty/27647/espumisan-krople/apteki

https://www.gdziepolek.pl/produkty/88424/ibuvit-d-600-krople/apteki

https://www.gdziepolek.pl/produkty/16163/cebion-krople/apteki

https://www.gdziepolek.pl/produkty/11562/biogaia-protectis-baby-krople/apteki

In cities such as Warsaw, Wrocław, Katowice, Kraków, Lublin, Gdańsk, Łódź, Szczecin, Białystok, Poznań and Chorzów, products can be ordered with instant delivery in as little as 1 hour thanks to the Wolt Drive service.

Check if the service is available in your location:
https://www.gdziepolek.pl/koszyk/szybka-dostawa?src=zf

I've attached links to helpful entries:

https://www.gdziepolek.pl/kategorie/probiotyki-dla-dzieci

https://www.gdziepolek.pl/kategorie/witaminy-i-suplementy-dla-dzieci