Unfortunately, most of the options above are as you stated “laborious”…
(I recommend you explore them anyway because there are sooo many more things you can do besides just unlocking doors 
)
Here is my simple suggestion for your specific use case besides IFTTT: (1) Create a virtual button that, if pressed, triggers a Smartthings routine that unlocks the door. (2) Create a Alexa Routine in the Amazon Alexa App to that presses the virtual button.