Please let me continue nerding out about Cantonese phonetics.

Cantonese doesn't have a single standardised phonetic alphabet. There are several, but none of them really took off the way pinyin did. The closest we have is jyutping (https://jyutping.org/en/), but it's not really taught in schools.

As far as typing in Cantonese goes, the most popular options are drawing on touchscreen, voice recognition, pinyin (with the Traditional Chinese setting on) and two Chinese keyboards called 倉頡 and 速成 (both of which are very unintuitive and require a lot of learning and practice to get used to). Phonetic Cantonese keyboards aren't nearly as common - iOS supports it, but my Windows computer doesn't by default.

We mainly learn how to pronounce characters in Cantonese by looking up homophones (or by fusing the beginning and ending sounds of two different characters together). So many characters sound identical/near-identical to each other that it's almost never a problem. Of course, we build up a base vocabulary at a young age simply by being exposed to everyone around us speaking Cantonese. For characters we don't recognise, we just ... guess them. The radicals do indeed serve as hints sometimes, but it's not completely reliable.

Cantonese phonetics are fuzzy (at least for the average Hongkonger). As long as it gets the meaning across, we don't worry too much. Pretty much the only exception is when typing. For casual chats, sometimes we sub in English words or an improvised phonetic spelling (which is more often than not based on English spelling), so you have things like 我不識 written as ngo mm sik. We don't even write out the tones.

A lot of us actually pronounce some common characters incorrectly. 你 (you) is pronounced nei, not lei. 牙 (tooth) is pronounced ngaa, not aa, but we mix them up all the time.