Wondering whether Canada & BC might domesticate UNDRIP seems besides the point since UNDRIP itself explicitly recognizes the sovereignty of settler colonial states (above Native sovereignty) in Article 46. Article 27 recognizes colonial law as able to "adjudicate" Native rights.
Canada & BC (for the most part) have not even been parties to the many Treaties involving Indigenous peoples on these territories, let alone respected or adhered to them. Treaties are ostensibly international law, while UNDRIP is not.
Most of BC has no Treaties. BC is a rogue province that was formed in violation of the Royal Proclamation of 1763 & Duty of Disallowance of 1875. The modern BC "treaty" process was started in response to the many Native blockades in the 1980s & 90s (more than any other province.)
At the time of adopting UNDRIP last year, BC's Premier & Minister of Indigenous Relations publicly stated that First Nations would not have a "veto", that Native rights were the same as those "all peoples" have, & that Bill 41 doesn't give UNDRIP "legal force and effect."
BC's adoption of UNDRIP is not a conspiracy or trojan horse. It's conducted openly in collaboration with the settler corporate community. As the CEO of the First Nations LNG Alliance said, “I see UNDRIP creating more certainty. I’m hoping that investors hear this message."