These are huge and public companies and are lots of regulation and scrutiny by the government and investors and are a big target for hackers and adversary governments and that's why they spend a fortune to keep their reputation clean. I don't think you should compare yourself to them.

>VPN or Cloudflare's Access solutions you are talking about, are designed for other purposes

What other purposes? please enlighten me

>The most important thing is that you don't need to install any additional software on the client machine or server

so your product works by authenticating uses via your webapp's SSO for example and then the client has to manually download the private keys and certificates and use them with the ssh command?