Let's explore this idea that the agreement Johnson signed is somehow "unworkable".
The Brexit deal that he signed was designed specifically to meet UK red lines and demands places NI effectively within the EU single market. It wasn't their decision to divide the country into two different trade zones – that was ours. There was a temporary solution for some food exports to give the UK time to prepare and that is coming to the end without the UK having done anything - sound familiar?
The British government is acting like this is an outrage to whip up people who are either anti-EU zealots on any basis or can't be arsed to inform themselves – but there's nothing new here it was exactly what was signed. It all comes down to Johnson not wanting the ERG to see him align with EU food hygiene standards, despite knowing this was coming.
As for the DUP, well they supported something for their own purposes that the majority of their population rejected, they have made themselves irrelevent and have demonstrated where trust in Johnson gets you. The EU might have spotted that, as if they needed any more evidence of his duplicity.
Yes, you're recycling once again the fact that Johnson signed the NIP. We know that. Together with its subsequent passage through Parliament and the EP, it does make it law, but it doesn't therefore follow that it's workable, which at the moment, it patently isn't. The reason for that is the manner in which the EU has chosen to apply it, which is apparently overzealous and is directly leading to difficulties in NI, and which breaks at least three of its own clauses, which are constitutional rather than necessarily economic. The first (Article 1/1) relates directly to the GFA, and states that the Protocol is
'without prejudice to the provisions of the 1998 Agreement in respect of the constitutional status of Northern Ireland and the principle of consent, which provides that any change in that status can only be made with the consent of a majority of its people.' The unfettered movement of goods between the nations of the Union is written into the Acts of Union of 1709 and 1800, and in fact forms a major element of those Acts.
The second (Article 6/2) directly addresses the protection of the UK Internal Market, the relevant element of those Acts of Union, and states that
'Having regard to Northern Ireland's integral place in the United Kingdom's internal market, the Union and the United Kingdom shall use their best endeavours to facilitate the trade between Northern Ireland and other parts of the United Kingdom, in accordance with applicable legislation and taking into account their respective regulatory regimes as well as the implementation thereof. The Joint Committee shall keep the application of this paragraph under constant review and shall adopt appropriate recommendations with a view to avoiding controls at the ports and airports of Northern Ireland to the extent possible.'
The third (16/1) relates to Safeguards, and states that
'if the application of this Protocol leads to serious economic, societal or environmental difficulties that are liable to persist, or to diversion of trade, the Union or the United Kingdom may unilaterally take appropriate safeguard measures...'. It is clear that 'diversion of trade' is already taking place, because UK supermarkets are already sourcing goods for their NI outlets in the EU, and Amazon is now serving NI from a depot in Dublin. It is also clear that there are 'societal' difficulties. It is this final article that the Commission President, von der Leyen, unilaterally invoked in January over the vaccine issue, when she suspended the protocol, thereby both setting precendent, and demonstrating clearly that the EU is not as interested in the NI matter as its virtuous grandstanding would suggest.
The problem seems to lie in the definition of 'goods at risk', which the EU kept very loose in the NIP, and which the (strangely invisible?) Joint Commitee is required to oversee, as well as in the sphere of SPS checks.