'I don't think Gromit gives a damnd whether it's true or not...'
He is not alone there:
"...the agreement to a UN policy document on immigration recently endorsed (by May inter alia) at Marrakesh, which effectively gives any aspiring third world citizen the right to relocate himeself and his family to any rich democracy of his choosing and enjoy all the rights of that country's citizens. "
You refer to 'The Global Compact for Safe, Orderly and Regular Migration (GCM)' , "the Compact is not an international treaty, it will be non-binding under international law." ""The Global Compact reaffirms the sovereign right of States to determine their national migration policy and their prerogative to govern migration within their jurisdiction, in conformity with international law." -WIKIp
"The UK endorsed the deal and praised it as a way to tackle illegal migration as well as keeping migrants around the world safe
The government has been clear that the UN agreement will not change the ability of the UK to set its own migration policy.
The compact "protects every state's right to determine its own immigration policies, including in areas such as asylum, border controls and returns of illegal migrants", said Lord Bates, Minister of State at the Department for International Development.
Among those who refused to adopt the deal - in addition to the United States - were Hungary, Austria, Italy, Poland, Slovakia, Chile and Australia."
https://www.bbc.co.uk/news/world-46607015
Seems USA, etc. above were taking no chances in this non-binding Treaty, but it appears to have you worried v_e, again ?
https://www.theanswerbank.co.uk/News/Question1634452.html