Here's the Autohotkey script I have settled for using with my Apple Magic Keyboard 2 on Windows 10.
; AutoHotkey script to make Apple Magic Keyboard 2 (Bluetooth, released in 2015) usable in Windows
; Unfortunately the actual FN-key and the Eject key on this keyboard does literally nothing in Windows, so we can't use them
; The fundamental principle is to instead use Right Shift as FN key, and then use the printed media keys, and then
; some elements from the layout of POK3R Keyboards, such as "FN"+Backspace to Delete, and "FN"+P to Print Screen
; ("FN" is Right Shift ofcourse)
#NoEnv
SendMode Input
; Swap left Command/Windows key with left Alt (for alt-tab and muscle memory)
LAlt::LWin
LWin::LAlt
; "FN" mappings (...except R Shift is the FN key...)
RShift & Backspace::sendinput, {delete}
RShift & Right::sendinput, {End}
RShift & Left::sendinput, {Home}
RShift & Up::sendinput, {PgUp}
RShift & Down::sendinput, {pgdn}
RShift & P::sendinput, {printscreen}
RShift & U::sendinput, {pause}
; Media keys
RShift & F7::sendinput, {Media_Prev}
RShift & F8::sendinput, {Media_Play_Pause}
RShift & F9::sendinput, {Media_Next}
RShift & F10::sendinput, {Volume_Mute}
RShift & F11::sendinput, {Volume_Down}
RShift & F12::sendinput, {Volume_Up}
; RShift ESC to open Task Manager
RShift & ESC::Send ^+{Escape}
; show open apps in Windows 10 (similar to Mission Control in macOS), a bit glitchy
RShift & F3::send #{Tab}
; open task manager
RShift & F4::send {SHIFTDOWN}{CTRLDOWN}{ESC}{SHIFTUP}{CTRLUP}
; swap < and § (you may not need this)
§::<
<::§
The comment at the top pretty much sums it up, but the idea is to use the Right Shift key as a FN key. The Eject key and the FN-key on the keyboard does nothing in Windows (nothing reacts to it), so we can't use those. Therefore, I decided to figure out what the least used key was, and I determined it was the Right Shift.
Once we have a function key we can start doing some fun stuff, inspired by my POK3R Keyboard:
And then for media keys, I went with the ones that have the Media icons printed on them (F7-F12). Just use RShift to do the action that is printed on them.
This is what I have been using for the past week or two and I am quite fond of it. Especially the navigation stuff. I use my middle finger to push down RShift, and then I use my thumb to pick an arrow.
The last snippet is to swap < and §. You may or may not need it. Sometimes I've needed it and sometimes I haven't. Even when I use a PC keyboard in macOS I've sometimes needed it. I don't know why.