How to 'add' a new key to the keyboard?

I don’t know if this is possible to do in Plasma:
I’d like to add a new symbol (í) to my keyboard when double pressing y.

Background: I bought a Czech keyboard (don’t ask why lol) but would like to use it with a Hungarian layout. It’s missing the í key when using the Hungarian layout. It does have a key combination to type í (shift+ 9), but that doesn’t work with this layout set.

I could make this work with an AutoKey abbreviation on X11, but that doesn’t work Wayland.
Might there be a way to replicate that on Wayland?
I’d like it to type í when pressing y twice.

Looking at XKB data, Hungarian layouts have iacute at the third level of j and fourth level of i, so accessible as AltGr+j or AltGr+Shift+i.

You can see those via the preview button on keyboard layout selection on System Settings.

Thanks, weirdly this didn’t work before but now it does.
I just need to somehow map it to yy now

I ended up creating an abbreviation in AutoKey (qt) to achieve this