Hi @Leonardo.Willrich
As I understand, You don't want to change entire menu for tenant or host, just show/hide some menu items for host/tenant.
At this line I can show you a workaround:
//if (_currentTenant.IsAvailable) // How to do it? Or what is the best way to do that?**
if(_currentTenant.Id != null)
{
// tenant side
}
else
{
// host side
}
Host doesn't have Id and it'll be null for host. Honestly, It's not best way or recommended to check host tenant but might help for you.