First thing's first, the forum rules are English only, except in certain sections (like the LFG section), and this section isn't an exception. Just FYI.
Second, if I translated what you said correctly it reads:
A tutti gli esperti del gioco volevo chiedere il gioco è multi platform quindi tenere sempre lo stesso account/salvataggio per sia su telefono che su ninte switch. Fatemi sapere. Grazie.
To all the game experts I wanted to ask the game is multi platform so always keep the same account / save for both on the phone and on the nintendo switch. Let me know. Thank you.
To respond to that: It is multi-platform in the sense that it can be played on multiple platforms, not that the same save can be used on all platforms. There is no cloud save to access from multiple platforms (though PC players can backup their saves on Steam or GOG's clouds). For many platforms you do not have file access too, so can not copy your save to upload it to another device. On PC (both Windows and Mac), Android and iOs mobile you do have file access so can copy saves between these platforms. On the PS, XBox or Switch, though, you're sadly out of luck. If you want to be able to transfer back and forth, I'd recommend phone and PC instead of phone and Switch.
