According to this Reddit thread from 10 months ago, some major US banks like Chase won't work even in development mode without production approval, and some people mention obstacles getting approved for OAuth without being a company or otherwise having that level of security posture. (Other people seem to have gotten successfully approved for OAuth.)

I agree this niche needs a better solution than it currently has, although the commercial and regulatory incentives might not be well-aligned to force that. In my family we have important accounts in the US and in the EU (as well as less important accounts in Canada and Mexico), and I don't know of any personal use-friendly solution that lets me pull my data automatically from all of these.

I'd honestly like some nice integration between Plaid and Excel or GSheets to let me track capital gains transactions for my non-euro accounts in the weird way that German tax law requires (over a surprisingly broad range of accounts starting next year at the latest). But nothing turnkey seems to exist right now.