Samsung Galaxy allows you to send bluetooth audio to two different speakers at the same time. I was able to do this with my S21. It doesn’t really depend on the bluetooth speakers used, so you could test this out with your Roam and a different bluetooth speaker/headphones to test it out. It’s my understanding is that Apple does not have this feature.
It’s worth noting though that when you have a stereo pair of Roam speakers, putting one of them in bluetooth mode automatically breaks the stereo pair. You will need to turn off bluetooth and repair the speakers every time you want to go back to stereo.
Given that, in my opinion, if you want to use the Roam often as a bluetooth speaker, don’t get a pair of them. If you want to use Roam primarily as WiFi speakers, then a pair makes sense. If your habit requires a lot of both, and budget allows, you may want to get 3 Roams...a permanent stereo pair and one used outside of the home.
Mod Edit: Changed “stereo pair of bluetooth speakers” to “stereo pair of Roam speakers”, for clarity.