Votes are votes.
Expats voting in Pennsylvania have more power than residents voting in Alabama.
As far as SS and Medicare are concerned, there is zero doubt that democrats are much better.
As far as expat lobbying groups, that exists but yes very weak.
Most Americans consider expats as unpatriotic.
As far as annoying banking regulations that impact expats, I may be wrong, but I think the democrats are probably worse on that.
Also don't assume expats are voting only on narrow expat specific issues.
In my case, support for Ukraine over Russia, democracy over autocracy, voting rights, LGBTQ civil rights, reproductive rights, protecting the independence of the DOJ, common sense gun restrictions, affordable housing, keeping most federal workers based on competence and experience rather than loyalty to a president and others are all important concerns.