with Taiwanese Mandarin I mean 臺灣國語, also called 華語.
All I find online, given how relevant China is today is the simplified script and PRC vocabulary, not the vocabulary used in Taiwan.
Even translators advertised as offering Taiwanese Mandarin translate into Chinese Mandarin.
You wouldn’t be using pinyin for this.
Pinyin is specifically tailored for the Beijing dialect (which is now what you call mandarin) back in the 1950s. Other dialects or regional variants do not translate well into pinyin.
For example, Shanghainese and all Wu-style dialects have 5 tones instead of 4. If you’re using Pinyin you’re using the Beijing pronunciation.