I'd love to have that, but such a service has to comply with government regulations and payment systems requirements in order to issue virtual cards that are generally accepted. I can imagine a company that would open source their code, but what benefit would it be for you? You can't self-host it and you cannot audit their infrastructure to confirm they run exactly the same code they publish... You want trustless finances - go crypto and say goodbye to convenience and wide acceptance.

Otherwise, you have to trust a middleman. And if we are talking about trust, privacy.com looks trustworthy. They have paid plans, so it doesn't look like selling clients data is their business model. They clearly say they don't sell users data in their privacy policy, which makes them a potential target for lawsuit if they caught lying. They haven't been caught on anything nasty. Good enough for me. You do you.