The point of allowing Ukraine to use these weapons isn’t for Ukraine to strike deep into Russian territory. It is to deter Russia setting up logistics just across Ukraine and Russian border because they feel safe. This forces Russia to move their logistics centers further inward stretching out the line. Another reason mention in the video is to strike the bridge in the Kerch strait connecting Crimea and Russia.
NATO could have made this decision in secret and allow Ukrane to launch a surprise attack deep into Russia but that’s not what’s happening. It seems like everyone including PM of Canada is essentially broadcasting this new potential capability instead of keeping it a secret because NATO wants it to be a form of deterrent. This is why this is relatively safe move and will not escalate into anything bigger like a full on nuclear war.