About icu, I enabled it because I'm writing (already did it, just testing) a texlive recipe, and it needs harfbuzz + icu, so I enabled it to extend compatibility.
I didn't know it break crosscompilation, so no problem in removing it, just wondering about a future approach.
What are you using ICU for?
Harbuzz has a built in version of libUCDN it uses when ICU is disabled, which provides a minimal set of the unicode lookup and transformation functions it needs. You can access them yourself if you look at the hb-unicode.h header.
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