You don't appear to be able to hide the header bar when deploying the PWA. We use Edge Cloud Policies to deploy BC to our users. This policy is (conveniently) targeted toward our O365 Security Groups, which are used to grant permissions to uses. This way, we can truly centralize deployment.

We have not figured out a way to use the showheader=0 when deploying the web app. Also, we don't believe disabling the header should prevent users from changing companies with CTRL+O, but it does.

https://learn.microsoft.com/en-us/previous-versions/dynamics365-release-plan/2020wave1/dynamics365-business-central/new-url-parameter-hides-web-client-header