The length of time until election results are "official" is actually not unusual. The unusual part is that these state results are so close and we are all paying so much attention to it all. Normally, the margin between candidates is so large that it's easy to predict and so a winner is declared long before the votes are all counted.
I think that AZ and NV will report finals tomorrow. Sooooooo if both states get called for Biden (well technically AZ already was) then he becomes pres elect. The thing is that the media is delaying things
On that note, North Carolina won't be counting their mail-in and provisional ballots until the 12th. Chances are that unless the legal challenges extend the process, NC's results will end up not mattering at all.