Is there a way to see if our staff that are receiving Send Alert messages are opening them?

Well, this is something which is not possible OOTB since alert email recipients don't need to be in the database in the first place! However checkout Sandy's comment on this thread where he describes how this can be achieved by using Send Email flow step instead of the send alert email with a dedicated form that triggers off the email to sales by posting a webhook to the "loopback" forms endpoint. Check out Dan's post too that Sandy has linked in his comment, great read!