Say you have a laptop and a PC keyboard and want to have different settings for the internal and the external keyboard

It already lets you have different settings for the internal en external keyboards by default. I use it just like that - vanilla settings on my MacBook built in and for the external keyboard I switch command and option, since it’s a windows keyboard.

I don’t want to be inflammatory, but the amount of baby duck syndrome when people say MacOS and Linux are unusable is crazy. Just try to go vanilla for 2 weeks before you install two dozen utilities.

The settings in System Settings.app are per-keyboard, so you don't need anything external for that.

I use it to map caps lock to a hyper key[1], whether it’s an Apple keyboard or not.

[1] When I hold caps lock, the computer responds as if I’m holding Command + Option + Control + Shift.

In the “Complex modifications” tab, choose “Add rule” and enable “Change caps_lock to command+control+option+shift.”

Newbie Mac user here. I just did what you suggested (I believe it's basically what's suggested in this article: https://9to5mac.com/2016/03/17/how-to-remap-windows-keyboard...), but I don't think Ctrl+C and Ctrl+V works on browsers; I still have to use Alt+C and Alt+V to copy paste when using Chrome/Firefox browsers whereas Ctrl+C and Ctrl+V works in PyCharm.

What am I missing? Thank you in advance for your suggestion/reply!

If you run through that guide I think the intended result is that "Alt-C" is going to be your copypaste. E.g. the keys work in the Mac order: CTRL / OPT (ALT) / COMMAND instead of the Windows order (CTRL / WINDOWS / ALT). So using Alt-C should trigger Copy, matching Mac-user muscle memory.

Perhaps PyCharm is set to Windows keymappings or such?

The mac doesn't use ctrl modifiers to use copy paste. If you remapped Alt/option and windows/command keys on a windows keyboard alt-c & alt-v (i.e. the keys to the right/left of the spacebar) would be recognized as cmd-c and cmd-v on the mac. PyCharm supports a windows and linux keybinding that lets you use ctrl-c and ctrl-v to copy paste but the mac generally uses the cmd key as opposed to the ctrl key. If you want to use ctrl-c and ctrl-v you can remap both of those pretty easily using karabiner elements to cmd-c and cmd-v.

right-option to forward delete on the internal laptop keyboard.

I used to use it to remap capslock to control, but apple has since added that to macOS itself.

I use it to have hybrid modifier and regular keys: if I hold down caps lock like a modifier key and strike another key then it behaves like control. If I tap caps lock like I would a letter key then it behaves like escape.

Return is another hybrid between itself and control (my keyboard does not have a right control key).

Space is another hybrid with a whole lot of bindings when held down. With s it generates space so that I can have key repeat for space (don’t need that often). With hjkl it generates the cursor keys.

Does this help?

Okay that's a great suggestion. I didn't mention it but I do also change my caps lock to an extra escape key.

I use Caps lock as backspace. Go back a webpage, delete last character. Use it all the time. WHO NEEDS TO SHOUT?

for some reason apple think that the backslash and backtick keys are the opposite of what they actually are on british pc keyboards