That's because there are good reasons for running it in the recommended way. If you're going to go out of your way to run it in bad, unpopular ways instead then

That's because there are good reasons for running it in the recommended way. If you're going to go out of your way to run it in bad, unpopular ways instead then it's on you to get devices that support what you're trying to do. (For example, squid on Linux would do it just fine, whereas some random consumer WiFi/switch/router combo thing is probably not going to go far outside of its basic functionality.) Instead of giving up, I'd suggest doing it the normal way -- do DHCPv6-PD to get a routed prefix, use that on the LAN and route to the Internet. On most v6-capable routers that's the default and will happen automatically, and it would be hard to make it easier to roll out than that.