I'd definitely agree that this is overkill for most people. In your case, though, I think that you could put the same amount of work into GnuCash and get the same results without writing any code. Plus you'd have a GUI with built in reports and whatnot. Not sure if that matters to you.

In the article, I briefly touch on skipping manual transaction logging and just importing statements from your bank / credit card. And I gloss over this, but it looks like GnuCash offers similar functionality for automatically updating stock prices https://wiki.gnucash.org/wiki/Online_Quotes - not sure if it's a pain to set up or not, but it's probably not as easy as just calling a google sheets function.

Seems like you wouldn't have any reasons to switch over given that you've already got a nice system going, but just wanted to point out that you can use GnuCash in a way that's not quite as... rigid as the way I use it :)