Not sure about parent but here in Brazil all ISPs are still using PPPoE even under gigabit fiber, it's a miracle they can find a router that is able to push 800 Mbit under single-threaded pppoe. I've yet to find a router capable of doing proper gigabit that isn't some enteprise machine that costs me a car.

In cases like yours, the best solution is probably to get an x86-based fanless mini PC built around a laptop CPU. Those can hit quite high single-threaded speeds and have enough resources to handle not just your routing but also light duty as a home server. Chinese brands like Qotom and Topton and a bunch of others are selling them on AliExpress. They're several hundred dollars, but still cheaper than a lot of enterprise gear, and you can get them with 5 or 6 Ethernet interfaces. Getting a separate consumer WiFi access point/router with minimal CPU power of its own is usually cheaper than trying to add an AP-capable WiFi card to a mini PC.

And if you're going to do that, just run opnsense and (being essentially a distro of full blown BSD) have all the security, flexibility and scalability the machine can provide.

OPNsense security updates are delayed from FreeBSD ports by days to weeks.

It's not uncommon for DSL at all.

Yeah, but DSL won't have a problem with speed, and routers having too weak cpu to handle it.

GPON does.

A major Romanian ISP uses PPPoE and I'm tempted to say that another one does it too and they're offering gigabit speed.

Many fiber ISPs here in Europe seem to share the backend infrastructure between DSL and FTTH subscribers and that sadly also involves PPPoE encapsulation.