I have several “Things” which will soon be sent to remote locations. Mostly WiFi connections won’t be available. But user action ( at the remote sites ) can enable the wifi. Can an update be “automatic” if a revised sketch exists, or can an action performed to the “Thing” ( e.g. button press ) initiate a download ?
The best I can do is maybe. Without knowing what you have it is impossible to accurately answer your question.
Check into OTA (Over The Air) programming it may be what you want, Also a button press can start a download if your code supports that function.
I created several modes of operation, including “normal” ( when wifi is disabled to prevent the device seeking an SSID - and introducing lots of lag )… and an “ update mode” where wifi is enabled.
It would be useful if a version check ( a simple integer ) could initiate a Sketch update, or if an operator action ( shake the device ? ? could also do it?. … yes I’m using the IMU here 
normal mode : wifi disabled
update mode : wifi connection enabled
I’m not sure what you mean re “over the air programming” . I’ve added two video clips which illustrate my current progress - I need to add a function to the “wifi connection enabled” state, which will some how initiate an update.
Sorry I do not watch videos.
DuckDuckGo "Arduino OTA (Over-The-Air) allows you to upload code to your Arduino devices wirelessly, eliminating the need for a physical connection. This is particularly useful for updating devices that are hard to reach or deployed in remote locations." Using your search engine you will find everything you need even code.
This tutorial should help: https://www.arduino.cc/en/Tutorial/ota-getting-started
I am already using OTA updates, but I currently initiate the process by clicking on a “right arrow” in the cloud editor. What I need to know is :- can the OTA update be initiated by an action ( e.g. button press or something else that I can detect ) which changes a variable ( in my remotely located Nano33 IOT ) which then returns a change of condition to the ArduinoCloud to “trigger” the commencement of the sketch upload ?
Yes. People were doing this before the cloud.
That’s encouraging to know that it’s possible, now a little more insight ( in the context of the ArduinoCloud ) would be very useful i.e. how ? are there any code examples ? Does it require the use of the API ? I imagine that I’m not alone in wanting a function like this - has anyone actually built a function to initiate an update triggered by a “Thing”?
regards
John
Sorry I do not know and I do not use the cloud.