Minimum device for 10 Gbit fiber connection over PPPoE over tagged VLAN?

Hardware Questions and Recommendations
1

Would a Banana Pi R4 suffice?
Or do I need an octacore x86 CPU?

2

there's only one octa core CPU out there ?

3

First you need to find if your provider can provide you with GPON SFP+ adapter or it will be GPON media converter with 10GbE copper port. You can buy fanless industrial PCs with underclocked epyc or zen OR xeon or i5 with sufficient ports onboard.

4

I don't have the provider yet, but most likely they will just provide a closed router, so I'm thinking that I will replace that with a third party onu with either copper of fiber output, I don't need embedded extra ports.

I was interested more about what sort of cpu power is needed to handle that kind of connection with openwrt.