A: Regarding do I think that this is something that is possible: While the api connection can be learned as a beginner, it might get pretty hard to implement due to any sign in procedures. In my few minutes of looking at API's of other accounting software, they need not just a "OAuth" connection but need to sign in and have some GUI to do that. in Google Sheets, you can access APIs that are RESTful, or have some persistant database and authentication that you use in the URLFetchApp.fetch in Apps Script.

There are other integrations and middlemen for accounting software that might be able to pull this off because you can sign in through a simple GUI, which you could technically do with HTML in sheets, but then the user experience is rather bad.

So I would say it's technically possible, but I haven't walked through this specific path. IF they have APIs then you can absolutely access them after taking Spreadsheet Automation 101, which is a course inside of Better Sheets. It might just take a bit of time to figure out that specific API.