Is a 2.1 soundbar likely to accept a 5.1 surround signal?

I recently got a used, vintage 2011 HDTV (midrange Panasonic Viera) and bought a Roku Express 4K+ to pair with it (overkill on resolution, I know, but this was the cheapest one that will do WiFi 5). I’m otherwise wedded to the Apple ecosystem, so the Roku is new to me.

I have surround sound toggled on the Tablo (for the sake of my home theater in the other room), and I’d like to keep it that way, but on the HDTV with just its built-in speakers, the Tablo Roku app says, “Your Roku is reporting that it cannot play this Surround Sound video.” I understand why - unlike the iOS apps, or Safari on my Macs, the Roku will not transcode the surround sound to stereo.

Now, the HDTV does support HDMI ARC and will pass through the digital audio, so my question is, if I buy a plain stereo, 2.1 soundbar, like this one for example,

JBL Bar 2.1 Deep Bass | 2.1 channel soundbar with wireless subwoofer

is that likely to accept the 5.1 surround signal straight from the Tablo recordings?

No (99.9999% sure).

Well, drat.

The iOS app doesn’t behave quite like I thought, either. When I tried to Airplay from that to the Roku at Full Quality, I got video but no sound. With constrained bandwidth, however, it converts to stereo and plays fine. That’s a less than ideal workaround.

An Apple TV, however, will convert to stereo on the fly (verified), so score one for the more expensive streaming box.

Apple TV not being a sound bar though, right?

Not a soundbar, but given that the TV will play the stereo that the Apple TV provides (contra the Roku), I can be confident that a 2.1 soundbar will, too.

You were correct. Adding that 2.1 soundbar doesn’t help, so I’ll be replacing the Roku with an Apple TV.