Newbie questions

[TouchuvGrey]

Hello all

             i'm Mike from Australia and am considering buying a PineTime watch.

      i would prefer to sync/connect it directly to my linux compter. if necessary, through a 
Samsung  s21

        i get the watch in the post. i open the box. i charge it.

      What do i need to do after that ?   Their website is anything but clear.

     Are there any fitness apps that work with PineTime ?

        Does PineTime count calories burned ?

                                                                       Mike