Inclusion of more Latin writing system (Pe̍h-ōe-jī/Tâi-lô) in East Asia

I have read through the [GF Glyph Sets](https://github.com/googlefonts/gftools/tree/master/Lib/gftools/encodings/GF%20Glyph%20Sets) and would like to suggest the inclusion of more glyphs for [Pe̍h-ōe-jī](https://en.wikipedia.org/wiki/Pe%CC%8Dh-%C5%8De-j%C4%AB) and [Tâi-uân Lô-má-jī Phing-im Hong-àn (or Taiwan Minnanyu Luomazi Pinyin Fang'an, Tâi-lô for short)](https://en.wikipedia.org/wiki/T%C3%A2i-u%C3%A2n_L%C3%B4-m%C3%A1-j%C4%AB_Phing-im_Hong-%C3%A0n) for transliteration in Taiwan.

Suggestion of list can be seen in [POJFonts](https://github.com/aiongg/POJFonts), [justfont introduction (Chinese)](https://blog.justfont.com/2019/01/jinxuan-taiwan-letters/) or the Chinese version of Wikipedia [Pe̍h-ōe-jī](https://zh.wikipedia.org/wiki/%E7%99%BD%E8%A9%B1%E5%AD%97#Unicode_%E8%BE%93%E5%85%A5%E7%A0%81%E4%BD%8D) and [Tâi-lô](https://zh.wikipedia.org/wiki/%E8%87%BA%E7%81%A3%E9%96%A9%E5%8D%97%E8%AA%9E%E7%BE%85%E9%A6%AC%E5%AD%97%E6%8B%BC%E9%9F%B3%E6%96%B9%E6%A1%88#Unicode_%E8%BE%93%E5%85%A5%E7%A0%81%E4%BD%8D). Fonts that support these includes fonts in POJFonts repo, [Open Huninn](https://github.com/justfont/open-huninn-font/) and [WD-XL Lubrifont](https://github.com/NightFurySL2001/WD-XL-font).