Numpad Keyboard in BTT Remote?

I've been using BTT for ages now, though not nearly to its full potential. I searched the forums a bit for anything to do with numeric keypads/numpads and found some interesting posts, but none seemed to quite answer my question: Is there a numpad keyboard in the BTT Remote app? Or is there a way to make one...

One of the interesting posts that I found was a tutorial for building a numpad keyboard using Mac's built-in Accessibility functions. This is so close to being the solution I need; I just need it in the BTT Remote. If there isn't already a readymade BTT numpad, is there a way to build a custom numpad keyboard for the BTT Remote?

Another rather interesting post asked about mapping the numpad on the trackpad. Some replies suggested that there might already be an app for that, but I couldn't find any further information on the forum or a broad internet search. So if anyone knows anything more about that, I would be eager to hear it.

Ultimately, I need an external 10-key, preferably with some extra function keys. Most of the 3rd-party devices are made primarily for Windows compatibility, so all the extra buttons don't work with Mac. It would be great if I could just use BTT since it's on all of the devices that I carry with me anyway.

[edit] I just had another thought: might it be possible to add functionality to the 3rd-party numpad function keys using BTT? One particular device says that the page up/down keys don't work with macOS. I suppose it will depend if the Mac can see the keys at all?

I have an external windows USB number pad and just used Karabiner-Elements to remap the useless keys (I changed NumLock into Tab for easy entering in spreadsheets). In the same way, you could redefine the keys without having to use BTT / BTT Remote.