This information is definitely available from the gateway.
I’d prefer to use this instead of installing the speedtest integration for a few different reasons.
(1) I’ll get more accurate results on the Unifi DM SE where “accurate” means the closest measurement of the true bandwidth my ISP is actually supplying
(2) I’ll avoid extra load on my HA VM. My HA is running on pretty beefy hardware but it’s unnecessary to tax it more. I also route all my IoT traffic behind a VPN (and HA OS is on that as well) so accuracy won’t be as good.
(3) Finally, the native HA speedtest integration isn’t super accurate. For best results I’ll need to also install the speedtest addon from a custom repository and it’s just more complexity (even if trivial) and load when I can just get the result from the Unifi gatefway ideally.
The only real downside is this is coming from the HA system, so if you’ve got only 1gb network, that’s your peak, compared to your DM or XG or whatever where you might have a much faster up/down directly from your ISP.