@a1ba @lanodan Japan still widely uses PPPoE over up to 1Gbps FTTH. Yes, it's terrible and most providers are pushing IPoE these days... but you still get PPPoE credentials from ISPs, and it's often the only way to get a public IPv4 on consumer contracts (IPoE is usually v6 only with some CGNAT based tunnelling tech for v4). The PPPoE access concentrators are horribly oversubscribed, so you never get proper throughput over PPPoE these days.
For 10Gbps FTTH they gave up on that thankfully, at least for normal consumer connections.
@a1ba Australian FTTH is IPoE at 2.5Gbps media speed for the new customer premises equipment. The only downside of IPoE is the need to manually enter the contracted service speed in order to shape egress packets correctly (eg, I am paying for 0.5Gbps ingress, 0.1Gbps egress). Can't find that there's a DHCP parameter for that.
There's no authentication. Just IPv4 DHCP and IPv6 stateless autoconf for the link addressing with DHCPv6 Prefix Delegation for the premises interior addressing. The IPv6 is nice, as that allows home equipment to run as a server without port forwarding, just a hole in the router's firewall (which commercial routers implement statefully, but there's no real need, and a homebuilt router can do it statelessly, and it's weird the first time you reboot the router and all the sessions stay up).