https://www.coursera.org/learn/learn-chinese-mandarin
There's this Coursera course from National Taiwan University, but I haven't taken it so I can't say if it's any good.
Honestly, Taiwanese Mandarin isn't that different from Mainland Mandarin, it's like the difference between American English and British English, there's an accent, and just a few vocabulary, pronunciation, and tone differences, but they're both the same language and if you learn one you'll have learned the other, and it will be easy to understand the differences between them with just a little research.
Most Taiwanese Mandarin teachers tend to speak with a more "standard" accent anyways than with a Taiwanese accent. Same for news presenters and such on TV. For more entertaining shows, not only do they speak Mandarin with a Taiwanese accent, but they often speak in Taiwanese Hokkien (also called Minnan, or just Taiwanese in Taiwan) which is not mutually intelligible with Mandarin, meaning you won't be able to understand a thing they are saying unless you learn it separately.
As for the characters, you can learn both simplified and traditional at the same time, which I would recommend, even though I think traditional characters look nicer and I enjoy writing them more, people from China often get offended by them for political reasons, and it does also enable you to read things from China more easily as well. The Pleco dictionary app (required for anyone learning Chinese) can show you both simple and trad when you look up words.
Hanyu Pinyin is easier to learn quickly than Zhuyin Fuhao if you've never dealt with non-Roman letters before, and is generally more widely used in the west, although Zhuyin is linguistically more appropriate as a phonetic system for Chinese (again, depending on your political affiliation).
It's hard to find books from Taiwan in the west, since Taiwan has been an international pariah since they lost their UN seat to China, and they don't have Amazon there. There's this website, but since you don't know Mandarin yet it would probably be too hard to use. You could try checking your local library for any Taiwanese Mandarin books. I know Taiwan used to have a Taiwan Academy scheme to try to compete with China's Confucius Institutes, but I don't know if that went anywhere.
Of course, if you really wanna sound like someone from Taiwan for some reason, u bettah move to Taiwan and get real gud quick.