Apple has intentionally dumbes down the iPad. It’s sad…
Edit: F keys as in F1-F12
iPadOS was born out of iOS. Why would iOS build support for F keys? F keys themselves are a hold over from quite a while ago. Apple tied to repurpose that space on the laptop with the old Intel MacBook Pros. When building a new OS, with a new software keyboard without F keys, why would they spend time developing around something that didn’t exist? When adding keyboard support, why would they add support for keys that don’t exist on the software keyboard?
I can see where that would be low on the priority list. I don’t think anyone at Apple had F keys working, then actively deleted the code to handle it while laughing maniacally.
Modifier keys (Caps, Ctrl, Opt, Cmd, Globe) on Magic Keyboard can be remapped in Settings.
SecureShellfish (ssh client) has a keyboard bar, support for Function keys.