Mmm, you may have a point, but you're going to have to be more specific.
I went to look at my Anker Bluetooth keyboard.
The "triangle pointing keys" nicely generated DPAD_DOWN etc.
With the "Fn" they generate PgUp, PgDn, Home, End, but only if you had put it in Android mode.
You have to hold down Fn and hit an S (which has the notation Android).
My other Bluetooth keyboard doesn't have this setup aspect but generates (Android) standard keypresses all the time.
If we're talking keyboards, you should really download UsbMode.apk from my sig. It will show you what key you are generating.
Maybe you should look for "full size bluetooth keyboards"?
https://www.amazon.com/Microsoft-QSZ...dp/B07Y3ZS47V/
If you want to stick with the smaller keyboards and don't want to use the Fn key you'll have to remap some keys.