You can not add a “y” to most nouns, in speech or writing.
Some words, such as salty and lemony, can be used in both speech and writing.
I think you can more generally convert nouns to adjectives by adding “-like”, but you can’t do that with all nouns either.
This wine is too fruity.
I’m not eating them. They look too much like pomegranates.
Are wallabies kangaroo-like?
Did you buy a Honda Civic? It’s Civic-like, but it’s actually a Subaru.