It’s rare for Sonos to announce feature enhancements in advance and there are no rumors of stereo bluetooth soon or at anytime.  It’s not known (to me anyway) whether the Roam even has the hardware needed for stereo bluetooth.

My biggest complain is not even that is is not supported (although it is a problem indeed), but that this KNOWN limitation is not mentioned anywhere on the product page and customers like myself learn about it only after the purchase

But that’s not what you talked about in your original post.

From the product page under the FAQ section:

Clearly conditioned that stereo pairing was available when on WiFi.  Could they have more explicated stated that  pairing doesn’t work on bluetooth?  Sure.  I don’t put too much blame on marketing departments for not highlighting all the things the product doesn’t do. I don’t put too much blame on consumers making assumptions either, or using the return policy when the device doesn’t do what they need it to.

You can actually do this since update 14.16 https://support.sonos.com/en/article/release-notes-for-sonos-s2

14.16

Release date: 9/20/2022

What is the latency when one does that?  The standard BT latency of 20-40ms or is it 75ms minimum since it goes through the Sonos sync process?

It only means stereo pair will re-establish itself once you are back on WiFi (which makes it just a simple bug fix) 

Bluetooth stereo still doesn’t work outside of home WiFi