Classe

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Cliente.Models.Entities
{
    public class Orcamento
    {
        public string Nome { get; set; }
        public string ValorMaximo { get; set; }
        public string Mensagem { get; set; }
        public string Prazo { get; set; }
    }
}

View

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
             x:Class="Cliente.Views.Orcamento.OrcamentoMensagem"
             Title="mensagem">
    
    <StackLayout
        Margin="10">
        <Label Text="Nome" VerticalTextAlignment="Center" FontSize="Medium"/>
        <Entry Placeholder="Escreva seu nome" Text="{Binding DadosOrcamento.Nome, Mode=TwoWay}" HorizontalOptions="FillAndExpand"/>
        <Label Text="Valor máximo" VerticalTextAlignment="Center" FontSize="Medium"/>
        <Entry Placeholder="0.00" Text="{Binding DadosOrcamento.ValorMaximo, Mode=TwoWay}" Keyboard="Numeric" HorizontalOptions="FillAndExpand" />
        <Label Text="Prazo" VerticalTextAlignment="Center" FontSize="Medium"/>
        <DatePicker 
                HorizontalOptions="FillAndExpand"
                Date="{Binding DadosOrcamento.Prazo, Mode=TwoWay}" 
                MinimumDate="{Binding PrazoMinimo}" 
                Format="dd/MM/yyyy">
        </DatePicker>
        <Label Text="Mensagem" FontSize="Medium"/>
        <Editor Text="{Binding DadosOrcamento.Mensagem, Mode=TwoWay}" HeightRequest="150"/>
        <!--<Button Text="Solicitar orçamento" Command="{Binding SolicitarCommand}"  />-->

    </StackLayout>
  
</ContentPage>

ViewModel

using Prism.Commands;
using Prism.Mvvm;
using System;
using System.Collections.Generic;
using System.Linq;
using Cliente.Helpers;
using Cliente.Models.Entities;
using Prism.Navigation;
using Prism.Services;

namespace Cliente.ViewModels.Orcamento
{
	public class OrcamentoTabbedViewModel : BaseViewModel
	{
	    private INavigationService _navigationService;
	    private readonly IPageDialogService _dialogService;
	    public DelegateCommand EnviaOrcamentoCommand { get; set; }

        private string _nome = Settings.UserNomeSettings;
	    public string Nome
	    {
	        get => _nome;
	        set => SetProperty(ref _nome, value);
	    }

	    private string _valorMaximo;
	    public string ValorMaximo
	    {
	        get => _valorMaximo;
	        set => SetProperty(ref _valorMaximo, value);
	    }
	    private string _mensagem = "";
	    public string Mensagem
	    {
	        get => _mensagem;
	        set => SetProperty(ref _mensagem, value);
	    }

	    private DateTime _prazo;
	    public DateTime Prazo
	    {
	        get => _prazo;
	        set => SetProperty(ref _prazo, value);
	    }

	    private Models.Entities.Orcamento _dadosOrcamento;
	    public Models.Entities.Orcamento DadosOrcamento
	    {
	        get => _dadosOrcamento;
	        set => SetProperty(ref _dadosOrcamento, value);
	    }

        private DateTime _prazoMinimo = DateTime.Now;
	    public DateTime PrazoMinimo
	    {
	        get => _prazoMinimo;
	        set => SetProperty(ref _prazoMinimo, value);
	    }

	    private List<EmpresaLista> _listCompanies;
	    public List<EmpresaLista> ListCompanies
	    {
	        get => _listCompanies;
	        set => SetProperty(ref _listCompanies, value);
	    }

        public OrcamentoTabbedViewModel(INavigationService navigationService, IPageDialogService dialogService)
        {
            DadosOrcamento = new Models.Entities.Orcamento {Nome = Settings.UserNomeSettings};
            _navigationService = navigationService;
            _dialogService = dialogService;
            EnviaOrcamentoCommand = new DelegateCommand(ExecuteEnviaOrcamentoCommand);
        }

	    private void ExecuteEnviaOrcamentoCommand()
	    {
	        var empresas = ListCompanies.FirstOrDefault(l => l.EnviaOrcamento);
	        if (empresas != null) _dialogService.DisplayAlertAsync("Oops", "Selecione alguma empresa", "OK");


	    }

	    public override void OnNavigatingTo(NavigationParameters parameters)
	    {
	        if (parameters.ContainsKey("listaEmpresas"))
	        {
	            ListCompanies = (List<EmpresaLista>)parameters["listaEmpresas"];
	        }
        }
	}
}