#2. Or, even Apple TV? I don't know anything about it. But, AirPlay is an Apple thing. Why not use an Apple streaming box?
I doubt Roku will roll out AirPlay for older tvs. I think you'd be waiting for no reason.
"People are often amazed at how much we’ve done with the number of engineers we’ve got." (Roku CEO Anthony Wood, Austin Statesman, Oct 4, 2019). "Amazed" is one way of putting it.