You are not an ISP, the ONT (and OLT) is not worth thinking about because you have no control over it.
If you have a Gpon ONT and want to go to 10Gbps then the ONT would need upgrading, yes.
So how does it route traffic from any of the other ports? I think you might want to do a little bit of research into routing and switching.
Correct. And that’s the only difference. So if I configure the router correctly, any port can be the WAN port.
And of course, if you’re running IPv6 you don’t need to be on a separate subnet.
Can’t you just do a port forward so that LAN port 1 goes straight to the WAN port?
That won’t stop people ordering it...
It's just a cheap way to grab headlines. Gigaclear 'announced' their 5Gbps plan back in 2016 but it's not on their website