Which macOS versions support Office 2019 HB?

Office 2019 for Mac (all editions, including Home & Business) reached end of support on October 10–13, 2023

https://learn.microsoft.com/en-us/lifecycle/products/microsoft-office-2019-for-mac?utm_source=chatgpt.com

As Owl-53 has already mentioned, the limiting factor is coming from Microsoft, not Apple.

However, to directly answer your question:

At launch (2018–2019 era) Office 2019 was originally supported on:

• macOS 10.12 (Sierra)
• macOS 10.13 (High Sierra)
• macOS 10.14 (Mojave)

As macOS versions advanced, support shifted forward:

• Catalina (10.15)
• Big Sur (11)
• Monterey (12)

At that same time, older systems (e.g., Sierra, High Sierra) lost support.

From what I gleaned from the Internet, Big Sur was the last version of macOS that was fully supported by Microsoft for Office 2019.