question

This is a good question and I'd like to see more comments on that.

First of all, InfluxDB and Grafana in Home Assistant is something you can do, and is well documented elsewhere. (HA community, YouTube etc)

But the data you want to collect, won't be coming from VRM, but instead directly from your Victron GX device.

Here's a topic to get you started:
https://community.victronenergy.com/questions/63997/home-assitant-integration-with-victron.html

To connect Home Assistant and Victron GX together, I think you have three main choices:

- Modbus-TCP

- MQTT (and there are different ways you can do this)

- Node-RED in Home Assistant, directly linked to your GX device.

With Modbus-TCP, you have to set the refresh rate for information to come through. From my experience, you shouldn't set that to lower than 5 seconds, or you start to run into timeout issues.

With MQTT, this is what your GX device uses to share data with VRM.

And correct me if I'm wrong, but:

When you open VRM, and the "Last updated" field shows "Realtime", VRM is in practice receiving realtime MQTT info from your GX. Meaning, if you enable MQTT over LAN (from the GX Console) you will be sending realtime MQTT data to VRM, all the time.

So an alternative would be setting up Node-RED in VenusOS Large, and from there, set up an MQTT link to Home Assistant, sending only the sensor data that you need. This way you don't enable MQTT over LAN, and you keep VRM as is. See:
https://www.victronenergy.com/live/venus-os:large

And finally, you can have Node-RED in Home Assistant, and you can link that to your GX.

This option is more technical and sensitive. Read this carefully:
https://github.com/victronenergy/node-red-contrib-victron#installation-and-usage
https://community.victronenergy.com/questions/14801/externalexisting-node-red-connectivity-to-venus-os.html
https://community.victronenergy.com/questions/35001/external-node-red-on-ubuntu-connecting-to-ccgx.html