https://www.civicsearch.org/ pulls city council transcripts from YouTube etc

If your Home Assistant has Bluetooth, and the Aranet4 has the "smart home" integration enabled (via the app settings), then HA will pick up ambient broadcasts of the sensors out of the box. You don't need Zigbee or explicit pairing.

But I don’t have a large enough BT “network”, my zigbee networks spans my house (and entire premise).

Also there is a Go equivalent (https://pkg.go.dev/sbinet.org/x/aranet4) which works well on Linux and https://github.com/ryansouza/aranet4-exporter-go can be used to export the data to prometheus.

You're not limited to the Aranet4 app. The device speaks Bluetooth and there are Python and Go libraries for parsing the protocol. There is also a Prometheus exporter for it.

Home Assistant already has an integration to read from it as well.

You will need a BT -> HA relay, but you can do that with any ESP32 board and ESPHome.

I'm running hass on a raspberry pi 4 and its built-in bluetooth works fine, no extra setup needed.

Only for huge distances. I have mine connected directly to the BT of the mini pc I use to host HA.

Yeah, I'm running HA on the server that I use for all home services, so I needed the BT relay.

Great product. You can get data into Prometheus with https://github.com/ryansouza/aranet4-exporter-go too.