Background: I know it is possible to read/write data from/to a Google sheet using the JavaScript API. I know it is possible to do it with an API key paired with oAuth (because the service has to know who the user is, which really means being a google user).
However, the question that Google does not address clearly (and I find the documentation misleading):
Can a JavaScript app/webpage have write permission to a google sheet (that is public open access) WITHOUT having to provide an oAuth client ID?
Everything I tried and researched leads to no, you cannot - you have to provide a client ID. Also I find the Service Account method not applicable for JS API via a web page.
Am I missing totally missing something? Please let me know if you have any specific insight into the above.
I solved it by having middleware php code that takes data from the webpage and uses a Service Account to communicate with the Google sheet, then returns data to the webpage. So... my question re-phrased: can I do the above directly without php?
After testing it seems that there is no way to use Sheets API without getting some sort of consent being either through a consent screen or by using an API Key, your code will either have to show a consent screen to grant authorization or as you are currently doing, perform domain wide authority with domain wide delegation.