You want to write the arrow with your keyboard while typing in Obsidian, did I undertstand right ?
What is your OS ? If you use Windows, I may recommand you a mapping keybord tool, working for every software you would use on your computer. It is called “Clavier+” and it allows you to use whatever key for whatever function you want. Inside the software, you just have to select “write text”, type the text you wish to see (your arrow) and add the keys you want to associate with.
Apologies if I wasn’t clear enough, I would like to insert the symbol “↑” and “↓” , using a keyboard shortcut. Currently I have to copy and paste. I’m using Mac OS
I don’t have MacOS and no possibility to test tools for you, however I find something that should work fine : Karabiner. It’s free, open source and the last update was on Novembre, 2021 so it is updated.
But it seems that mapping custom shortcuts on Mac is much easier than Windows. There it is a tutorial to try it yourself, maybe it would work for you as well : tutorial