No, the only Sub that can be ‘bonded’ with a Sonos Arc is either a Sonos Sub, or a Sonos mini-Sub. Echo devices are not made by Sonos. 

So is this not true then

The original text can be found here: https://automatedoutlet.com/does-echo-work-with-sonos/

“Sonos opened the door for all of there speakers to be controlled by Amazon Echo or Echo Dot on October the 4th.”

While I do question this site (it does all seem a bit AI to me) It does not mention the Echo sub - that looks to be an addition to the Echo system- but only Echo devices that can control Sonos. Controlling Sonos via Alexa works. Adding a non-Sonos wireless sub like the Echo sub does not.