The only thing I'd mention is that the Governor in Council makes the regs on the minister's recommendation, but the Governor in Council does not need to make them. It's a “may”. As you noted, if a first nation makes its own laws, then they may opt out of the regulations in whole or in part.
Evidence of meeting #131 for Indigenous and Northern Affairs in the 44th Parliament, 1st Session. (The original version is on Parliament’s site, as are the minutes.) The winning word was consent.
A video is available from Parliament.