A thought I just had ... would there be any constitutional issues for Congress to direct the US Virgin Islands, Guam, and the Northern Mariana Islands to hold presidential elections, and to allocate those 3 extra electoral votes to the winners of each of those 3 territories?
It's still not full equality for them, but it allows those Americans to have some say in the presidential election process, better than nothing.
No, since the 23rd Amendment permits Congress to direct the appointment of the 3 district electors however they see fit.
The amendment specifically says "District constituting the seat of the Government," which means this trick wouldn't work
Why wouldn't it? The amendment
specifically says that "[t]he District constituting the seat of Government of the United States shall appoint [electors of President and Vice President] in such manner as the Congress may direct." Nothing therein precludes Congress from directing an unpopulated nominal "District constituting the seat of Government of the United States" to appoint each elector per the results of "presidential straw polls" in the 3 hitherto aforementioned territories. To be sure, it'd certainly be facially unorthodox, but by no means is it actually precluded by the 23rd Amendment's wording.