Well, I can certainly tell you as an anerican exist, the republicans did nothing to ensure the 4 million plus Americans registered to vote in advance of the election, advise Americans how to ensure their votes were received and counted (checking in case signature verification or additional ID was needed) - but the democrats abroad did.
As soon as Trump started the funny business changing the post master general and withdrawing sorting machines, communication about ensuring everything was up to date to vote from abroad started.
They also kept up adverts and emails to make sure all Georgians abroad who were able to vote in the run offs, did so. Also ensured they knew how to check their vote got counted and how to find out/rectify any issues.
Then there are the FAWCO clubs - federation of American women’s clubs overseas. Thousands of members. They started ensuring members had their mail in ballots organised months in advance with advice how to ensure their vote got counted
These are Americans abroad - students, military, military wives, employed abroad/wives of those employed abroad, missionaries, embassy/consular staff, or American citizens living abroad for whatever reason.