I wrote a very simple O(N^3) algorithm to determine that: for each possible actual word and the guessed word, figure out whether or not a word is eliminated. Then calculate a score based on how many words can be eliminated from a particular guessed word, averaged over all possible actual words.
(I originally thought O(N^3) would be way too slow to be useful. But it runs fast enough with a few thousand words.)
Like a sibling comment, I also found that the best initial guess is RAISE, although when I tried a different word list, I got different words like LARES (I don't think it's in the Wordle list).
One thing that surprises me is that by the time you get to the mid-game stage (after 2 guesses or so), occasionally it can be more optimal to guess a word with repeated letters; I did not originally expect that because I thought repeated letters are wasted opportunity to test more letters, but it turns out Wordle's handling of repeated letters can give you helpful information about the number of occurrences of a letter. (For example if you picked a word with 2 a's, the first one can be green the second one can be black, essentially telling you there is exactly one letter "a" in the word.)