Keyman VS VC Starter Kit

Keyman is very popular among linguists, if you still prefer a keeb that will input IPA Unicode by itself, you can get a QMK compatible keyboard (like this), but you'll need to program it, as in write the code yourself. Source: about 1 year ago

SIL's Ukelele is a popular app for creating custom keyboard layouts on macOS. SIL also recommends Keyman if you're looking for a cross-platform app for creating custom keyboards. Keyman already supports thousands of languages so they might already have a keyboard for the languages you need. Source: over 1 year ago

While I haven't used it myself, I have heard that Keyman is highly flexible and extensible, so it may allow OP to create a layout in its own format that has the desired behavior. Keyman was originally a commercial product, but SIL (which had long advocated its use) acquired it in 2015 and made it free shortly thereafter. The original developer seems to still be part of the team working on it for SIL. Source: about 2 years ago

For Tam Thư, specifically the phonetic Latin Quốc Ngữ and Ký Âm, I'm working off of an existing keyboard distribution platform called Keyman. It's free and open source with good developer's guide. For my case, Vietnamese typing is a bit complicated with many key sequences that makes modifications to a base glyph, and Keyman is a fit tool for that in my experience. It also follow the principle of "write once, run... Source: about 2 years ago

Because Tam Thư is in fact 3 writing systems combined, I made 3 separate IMEs/keyboard layouts for each of them: 2 phonetic keyboards for Latin Quốc Ngữ and Ký Âm Tự using Keyman, and 1 logographic keyboard for Hán Nôm (think of it as Vietnamese Kanji, you can read more about its history here) using Rime. This results in the user having to install both Keyman and Rime + my IME package for each of the two. Then... Source: about 2 years ago

Whenever I hear about Allbirds, I can't but laugh and think about this site: https://vcstarterkit.com. - Source: Hacker News / over 2 years ago