Umm... Unless this article is older than it looks, I'm pretty store that claim isn't entirely true, since this isn't really the first of its kind. VPNbook.com, FreeVPN.ninja*, FreeVPN.se, FreeVPN.me, and GenerousVPN.com all make similar claims, but not a single one of them claims to be the "first". AFAIK, all of these services predate ProtonVPN.
I did have some difficulty navigating their website, however. I do wish their website had been laid out better, since the download links for their OpenVPN config files were particularly hard to find. On a plus note, their website didn't require any third-party resources to function, which is somewhat rare these days. For this reason, there's no chance of Facebook, Google, or other surveillance-happy sites knowing who visits this site, when they visit, how often they visit, etc. ^_^
*FreeVPN.ninja used to be my favorite VPN service, but it no longer works. If you try to download an OpenVPN config file, you get redirected to another commercial VPN service. If you use old config files, they won't work.