I am wondering if Osibanjo can do any of these in Buharis absence.

1, declare the release of Nnamdi Kanu?

2, allow a memorandum for biafra.

3, allow regions or states control their resources and pay a token to federal government( restructuring).

Who can stop him from doing any of these?

He will definately respect international law unlike Buhari and will negotiate with them. He will also preserve the unity of Naija. My only concern right now, is his security arrangement level must have changed now.