I the meantime, most bookies have settled the bets with Biden as the winner. When do you think it will be finally settled on all betting platforms?
Betfair said they are
anticipating to resolve on Dec. 14 after the electors cast their votes (and I assume a few other bookies will follow this example),
Yes, it looks like freebitco.in is going to pay out after Dec. 14
according to this ^^^ today's post by TheQuin.
but some will run all the way until January 6th when the electoral vote results are announced.
Some of them will run ever further

, see the post by @Lucasgabd below.
regarding Betwrong question:
the website that will finish later, as far as I've seen is FTX, where the TRUMPGO and TRUMPSTAY contracts will stay online until 1st of February.
well, not complaining about easy money.
I read
this article , and it remains unclear to me, did they pay out Biden bettors already? It seems they, FTX, were so confident in Biden's win that they did.