Rome may provide her teaching with some Scripture references, but the only authoritative meaning these have is that which she gives them, based upon her premise of authority. Thus as regards what is the only supreme authority, Sola ecclesia is the alternative and the reality under Rome.
But without any authority to both determine the canon or interpret it according to the faith given by Christ to His Apostles, you end up with.. well what we have outside the Church.
So your premise is that an assuredly infallible magisterium is required for truth to be preserved, and writings to be established as Scripture, and for souls have assurance that men of God really are?
So how is assurance of truth realized? As Christ determined: by the Church He established as His body guided by the Holy Spirit to be the pillar and foundation.
And which is (conditionally) infallible. Asserting Rome is the answer avoids the problem of its basis. Most argue that being the instrument and steward of Divine revelation and inheritor of Divine promises, and having historical decent makes you the infallible interpreter of Scripture, and without whose sanction one cannot have authority. Is that your position?
Do you think the Church would have a canon that disagrees with the Church? :) This is tautology.
So your premise is that an assuredly infallible magisterium
My premise is the Church established by Christ with Him as the head and guided by the Holy Spirit to be the pillar and foundation of truth. You want something more? :)
Is that your position?
See above. It's also in Holy Scripture.