Yes. This is frustrating. Notable examples:

Updating an ESPHome device config requires network to build/compile the image. [0]

Viewing your Integrations page leaks a list of integrations you are using to "brands.home-assistant.io". [1]

[0] https://community.home-assistant.io/t/esphome-completely-off...

[1] https://community.home-assistant.io/t/wth-why-are-brand-icon...

Is the certificate for that domain pinned? If not, just host it locally. In fact, I'm going to try doing that. Have you already checked the Docs? Somebody probably already published a gist somewhere with the needed path

Locally hosting platform IO is definitely on my to-do list but it is a problem which looks vast.

I have SQUID doing TLS MITM in front of it right now, but that doesn't get me really to "offline builds".

A fresh HAOS VM can not successfully boot without internet access, maybe due to how they are managing everything with Docker within HAOS? I noticed this because the VM was accidentally put into a network that does not have stable internet, and I kept wondering why it didn't boot.

Really hope that there is a fully offline solution.

> The amount of stuff it pulls from the mothership and GitHub is crazy.

It seems the problem of HAOS, not Home Assistant itself. I have install my HA in NixOS from its package manager, it seems not try to download somethings.