Earlier quoted context omitted.
Please no. I used to have a Dutch ISP a few months ago that did not support IPv6 yet. (Odido. Same ISP that leaked my data in a big hack.)
Odido is the cheapest ISP for a reason. They refuse to implement anything that isn't strictly required. Perhaps implementing an Odido tax might actually make Odido care enough to throw the switch on IPv6. They bought 2a02:4240::/32, they just refuse to make use of it.
curl -v https://speedtest.ams.t-mobile.nl.prod.hosts.ooklaserver.net:8080
...
* Connected to speedtest.ams.t-mobile.nl.prod.hosts.ooklaserver.net (2a02:4240::e) port 8080