To put it simply, using unicode characters on a computer (or any smart device) is over-complicated. There are common situations (especially in STEM) that the inclusion of a unicode character in written media is useful and effective. From greek letters to math symbols to technical symbols, the unicode library is large (while also limited).
My initial solution has been to edit the .plist files of the Press and Hold accent feature (/System/Library/Input Methods/PressAndHold.app/Contents/PlugIns/PAH_Extension.appex/Contents/Resources/Keyboard-en.plist if anyone is curious) to make using unicode characters actually natural, but the safeguards apple has put up on more recent iterations on mac makes this tedious to update and makes edits. Another issue is that having anymore than 9 characters assigned per later is clunky. Also, having to remember which letter is assigned to which set of symbols is annoying.
My ideal functionality of this feature of BTT is a simple progression of the already built-in emoji widget. I'd like to be able to determine exactly which emojis (or unicode characters in my case) appear inside of this widget. My current work around is to add my character lists as favorites followed by 20 blank spaces. Sometimes these widget lags for me (I have a couple of folders for different categories) so I am hopeful that not having to have my 20 or so unicode characters followed by the entire emoji library would help that.
A bonus would be to go a step further and allow multiple characters to take the spot of a symbol. I have it set up as the accents for one of my keys that when selected it doesnt output a character, but a sequence of characters such as 15 digits of pi or the konami code.
TL;DR: I want to be able to chose a list of unicode characters/emojis to appear in the emoji widget instead of having to just use the favorites functionality.
It would also be necessary to support a different font so that there arent any missing characters.