You can't have your cake and eat it too. Everyone has agency, to decide who they interact with and who they give money to or, on the other side, who they sell products to/provide services to, and there are remarkably few exceptions to this rule (most based on things that the victim can't control). If a company wants to require you only use their products, or only use a allowlist of approved products, they can do that, just as you can decide not to use their services if they charge too much, perform unethical actions, or even if their company name contains the letter 'Y'.
Corporations are an artificial construct that we as a society let exist. We can decide to add additional restrictions to that existence like requiring them to not discriminate based on what software you run on your own devices.
but if I want, I can still create my own arbitrary security requirements and enforce them via software/audits
Try doing that to your bank or whatever other large company you interact with...