Hi There ,
I post this project but I don't know if it is really possible to do , so it is more a thought than a project for the moment.
I used to use a google sheets addon named gsm mailmerge
unfortunately this addon doesn't work anymore , I don't really know why , but it looks like the owner doesn't want to accept google T&C
I was not using all the features of this app , but only the mailmerge part
I'd like to know if it is possible to convert this addon to a script so I still can use it
I don't know if it can help, but I have crx file for this addon
Just let me know, thanks