A billion-dollar company cannot solve VPN on Windows? Please... The number and diversity of VPN offerings on Windows (including OSS ones) is a clear indication that that's not the issue.
Of course they can solve it if they wanted to. But those people were probably migrated to a more profitable team or laid off. We're in "number go up" mode now, not "market capure" mode.
i believe initially the vpn had something to do with google fi either integrated or a feature or something. so the vpn could be a leftover after they decided to go a different route, just a guess