> My parents smart Samsung is just a few years old, but, as I learned on my last visit, is no longer supported for many of the current streaming apps, so they need a new streaming device to plug into it!

I think a dumb TV with an external device is always better and hit this same path with relatives. The normal TV companies have no incentive to keep people happy for years with a dumb TV, so I use a laptop for TV and would only upgrade to a video projector.