It's an apt comparison.

Chinese writing is highly ideographic, but many hanzi contain a purely phonetic element, as a pronunciation hint.

Kana, a purely phonetic writing system, developed from hanzi, ditching the ideographic values.

It's actually the opposite: Chinese script is quite phonetic (with a lot of different base characters though) with some semantic hints. This is this way and not the other way around because of the historical formation of the main category of characters (形聲) in which new parts were added to do semantic disambiguation between graphemes used to write (quasi-)homonyms.

My impression was that 90% kanji are significantly phonetic but the remaining ideographic 10% are actually some of the most frequently used (上/下 and others)? Which is what I referred to as "a good chunk of it". But I don't know what I'm talking about:)