I know this is not a good way to get community approval around here, but: Chatgpt can write that for you. My bash-fu increased tremendously since it exists and I script everything now. In the past, it would end up with having an idea and also fear of failure. Now every scripting idea gets to be implemented and executed.

Have you considered using the at and shutdown commands together to accomplish this?

Edit: I have no idea why a few people downvoted my question. Maybe they misunderstood it?