@FlatSix911: There's one factor more - availability. We live in hard times. Even if some product is listed (such as Marathon Plus MTB) it is hard to buy it. I looked the tyre up and what is available for 700c wheels is the 2.1" only here, at the moment. I followed your advice to go with the Smart Sam 28 x 1.75" (regular ones) and should get them before the weekend. Thanks again for advice!
Same to
@TS25 - thank you! Some tyres could be imported from Germany but the waiting times are unacceptable.