To be fair, there is a big advantage with using Netflix's fast.com speed test:
Some ISP would have a list of speed test websites and unthrottle their connection to it. With Netflix's speedtest, if they do that, they also unthrottle Netflix as a whole.
Fast.com shows ping, loaded ping and upload speed.
It has a mobile app, but I didn't understand your point about VPNs.
You also get a sharable picture if you know how to take a screenshot 😂
The actual load test is from Netflix's servers and Netflix's domains. Open up the network tab in your browser debugging tool when running a speed test on fast.com and you'll see.
Netflix created fast.com to prove that some ISPs were throttling Netflix and hold them accountable towards their customers.
ISPs don’t see domains. Unless they control your DNS. I assume fast.com uses the same servers as Netflix and would have the same IP address, which would only be resolved to fast.com or Netflix inside Netflix’s servers. I think this is a fair assumption, as that’s the biggest benefit to Netflix. They want to prove your ISP is the problem not Netflix.
I host this for my own troubleshooting purposes. It works well enough. The other posters are talking about the Netflix speed test, don't forget cloudflare has one that also tests latency loaded and unloaded.