yeah, ddg BANGs are indeed insanely convenient, yet simple.
I especially enjoy that you can easily add your own BANGs, or even ask to ONLY use your custom bangs.
I wish there were more variables to utilize, though.

UPD: I'd like to reply to developer's response, but I couldn't find a way to do that. So I'm modifying my review instead.
Basically, there's an issue at project's repo right now, asking for regional bangs. I guess, I'd like to have something similar, but in a more general way: so that I could add some sort of suffix (possibly dash-separated) to an existing bang, and it would be available to me in the substituted quarry.
For example, !yt-@user@ would allow me to substitute for https://www.youtube.com/@@user@/search?query=@search@. I see how this can be problematic to implement though.

THANK YOU SO MUCH! i couldn't switch away from DuckDuckGo because i couldn't live without banging (😏), but this recreates it perfectly for other engines!

最高の拡張機能。
duckduckgoの豊富なbangシステムを自在に扱える

this is even faster than native ddg bangs for whatever reason. thank you for this!!

Changing prefix doesnt work

Wonderful

Easily one of the best extensions on firefox for somone who doesn't care about ddg indexing

Works perfect! Since it is open source we can chip in to fix future bugs, and improve it. Thanks!

Great add-on. Easiest way to have bangs without being forced to use Duck Duck Go.
The level of personalization is high and therefore very useful.