It would be extremely easy to have both. Tab to hide/show chrome and controls. The Affinity software does this, and it's intuitive and works flawlessly.

I presume the difficult question there, would be what you would expect users to do to engage with that mechanism on iOS (since many Apple first-party apps, e.g. Notes, are now designed once to run on macOS + iPadOS + iOS as essentially a single [responsive] UI.)