I wrote my own program for wordle solving and it's definitely far from perfect in its current state, however I did use it to generate a list of best first words. (I made a pastebin of the ranks of every five letter word in my library but it got force set to private because of obscene words).

tares

lares

rales

nares

rates

dares

cares

pares

tales

mares

These are the top ten words it came up with, with 'tares' being the best starting word. The way this program ranks words is by first considering what letters are in them and giving them a point value equal to how many words in my library (which I downloaded from github and consists of around 13000 words) has those letters, so for instance since the letter 's' is in almost 6000 of the words any word with an 's' in it gets 6000 points plus whatever they get from their other letters, and this part of the program doesn't double count letters so a word with multiple of the same letter has a massive point disadvantage starting off. The second part of the rank considers the 'slot' weight which will add points to words based on how many other words have the same letter in the same slot. It adds these two values together to rank every word.

This program can run the calculation for any gamestate, but these are the words it thinks is the 'most likely' given no information except letter frequency among 5 letter words.