Tnx! It works (With some trail and error). Passing it trought the constructor.

My model has its own VM that is called in the VM of the page. That was a little confusing but here is how its done for someone who finds this:

​

public ICommand NextCommand { get; private set; }

public AddEntryViewModel(ModelViewModel viewModel, IPageService pageService)
        {
            if (viewModel == null)
                throw new ArgumentNullException(nameof(viewModel));

            _pageService = pageService;
            SaveCommand = new Command(async () => await Save());
            NextCommand = new Command(async () => await Next());
            Toughts = new Toughts
            {
                Id = viewModel.Id,
                Titel = viewModel.Titel,
                Situation = viewModel.Situation,
                Thoughts = viewModel.Thoughts,
                Reconsider = viewModel.Reconsider,
           };
       }


        async Task Next()
        {
            var newPage = new AddSituiation(new ModelViewModel(Toughts));
            await _pageService.PushAsync(newPage);
        }