With the understanding that DIY is great, and this is a super-cool project, etc, we've used this [1] commercial door opener from Omlet (chuckle) with great results. Can be set to open/close at specific times, or manually, or after light/dark with programmed delay. No decapitations so far; auto-opens if there's resistance to opening above a mild threshold. Wifi connected if desired.

[1] https://www.omlet.us/shop/chicken_keeping/automatic_chicken_...