You definitely should, if they did; they have a number of similar pages for various games still in development.
There is a potential issue, though, with their TOS on purchase of such games: quoting from their FAQ ( https://support.gog.com/hc/en-us/sections/115000157529-FAQ-Games-in-development#... , 'What is the refund policy for games in development?'), '... Technical issues covered by the 30 Day Money Back Guarantee do not apply to games in development. Instead, you can return the game within 14 days of your purchase...'
In clear, that means that the period to get a refund (if there is an issue with the game) typically ends long before the game is available... fairly illegal terms here (consumers rights issues), so those pages are mostly advertising the game, I do not thing that many people buy early from them under those conditions.