The electoral college Is incompatible with rank choice voting. Even if you changed state laws to bind electoral voters there’s no great way to translate the ranked preferences of individuals into the into the ranked preferences of delegates.
So even if the EC was removed there is the lack of precinct summability. In the United States we have 50 separate elections that are counted and summed individually this would not work for RCV we would have to have a Central government to count the votes which is a security and political nightmare.
Score voting and Approval voting are both compatible with the electoral college although it would require binding delegates.
Score voting: super simple. Every delegate rates each candidate what they average was rounded.
Approval voting: slightly more complicated, each electoral delegate represents a % so if a state had 10 delegates one candidate would vote for anyone with approval over 10%, the best delegate votes for anyone over 20%… all the way to the tenth delegate who would get the honor of not voting got anyone who didn’t get 100% of the vote. This delegate would represent a great reminder that no candidate is universally supported and the actions of government should be tempered and humbled by the knowledge that they are to some small extent oppressing people.