You can use a laptop or a tablet. A big phone doesn’t bring anything new to the table. It’s just a sub category. Most people don’t need a tablet a laptop a phone and a large phone. Some might get something from it.
Only situation I’d see would be watching on a larger screen and maybe gaming. However I’d never need that as I have a tv. So why would I use a small screen? I’m sure it’s fun but I can never see it as something worth dropping 2k on.
Gaming laptop or a TV for gaming on. I wouldn’t play on my phone as it’s just a massive downgrade. But each to their own. Now a screen projected on my glasses. Sure.
Why would you ever play two idle games ? Sounds like an awful thing to do.