To those thinking this game is abandoned, they have been more frequent on their Patreon. As of February 19th, 2023, they have completed version 0.48. It was published last month on the 30th. Which is roughly 10 builds ahead from where the demonstration is available. It costs a mere $2 to gain access to it for a month. I do not know why they have not been updating their progress on here.
Short Answer: Kinda. They're still working on it and about half way there.
Long Answer:
As of May 28th 2023, they have reached the 0.52.3p update. You can find more details on their patreon page by clicking on the patreon image at the game page. Their latest post was made 4 days ago as a developer log with a majority of their posts being locked to the patrons and some additional information should you seek it. If it is in your means support what you like to see. It isn't too much to pay once and try out what they got. The 0.52.3p build was published back in April, no idea when their next content build is coming out. But I'd say the game could be finished within another year or more of development. Granted my estimate may be a bit too generous since I have no idea what their road map looks like.