As you've pointed out, UNDRIP is the result of decades of work by many people, including many indigenous peoples, and I think it's important when looking at indigenous law to understand that it changes with the times, according to the circumstances of the day. We have historical legal institutions and law as well as contemporary institutions and law, and people will continue to act on legal obligations through whatever forms are available.
As a tiny example of that, some of the justice initiatives in Canada look like regular justice initiatives, but when you ask people the why of what they're doing, talking to elders and many other people, they talk about the legal obligations they're trying to fulfill to the next generation, to the land, and to one another.
I think it would be a very interesting question to take UNDRIP today through an indigenous legal process and to look at whether it allows people to act on the legal obligations from their legal orders, and whether it informs decisions, because I think it will enable people to learn and change and continue to manage their affairs.