Can I play Fifa 19 with my friend although we both have different consoles?

Hi, I want to play Fifa 19 against my friend, but can we play even if I play on Xbox one and he plays PS4?

No.

Goes net, you could just see if various games are cross-platform (xbox / PC win10) and then there's one on the PC the other on the xbox (crossplay)

No, that is not possible.

I wonder again and again about such questions. Sure, Fortnite or Rocket League are a few crossover games but what do you think why different manufacturers produce different consoles?

To bind the customer to himself and his brand.