If you're willing to switch to a different input method, fcitx supports Unicode search: https://fcitx-im.org/wiki/Unicode

I mostly use it for trivial stuff like proper Unicode arrows → instead of ASCII ->, but I think it's pretty cool to have the option to type any Unicode character I want.

I use it but it always seems kinda "buggy" to select the desired char

Just mentioned in a comment myself: https://github.com/salty-horse/ibus-uniemoji