> It's hard to have it more reliable than this for me.
For me the main point of unreliability was the power consumption of the ESP while connected to WiFi despite my efforts to lower that in idle. I had no good option to have it plugged in and it would go thorough a battery pack in days. And I had no option for Homekit integration at that time, or anything similar, so everything was done locally over WiFi.
I had a fortunate scenario, living on the ground floor and in WiFi range but if you live 10 floor up, when you reach the building door the only way to reach your device is via VPN. Giving access outside your household was off the table. Every component you add comes with potential reliability issues, and every non-transparent component adds usability issues.
For me this wasn't a way for visitors to get in easier, it was for me and the family to do it conveniently without pulling out the keys, or in case you have no key (lost, locked inside).
The Nuki solved that, all-in-one package, always working connectivity, no additional infra for me to maintain except working WiFi, and easy user management. Just an easy app to control everything from anywhere. Downside is that Nuki has to keep their infra up and running. And it's less fun than building my own jank :D.