It might be best to call the ISP to confirm.
From how I read this diagram, if you are able to get a 1 Gbit plan then it will be either cable or fibre. In that case they will install a Network Termination Device which is the actual device that converts the signal into Ethernet. From there you can connect to your own WiFi router, or the NF20Mesh (but its modem functionality is unused).
1000/50 would most likely be a DOCSIS modem for coaxial cable, VDSL2 is for copper phone lines.
I would get one of the no-name Chinese 8-port RJ45 + 1 SFP+ switches based on the RTL 8373 that are cheap and use very little power.
What's your budget? The lowest cost Asus router with dual 2.5Gbe ports is the AX88U Pro:
https://www.newegg.com/asus-rt-ax88u-pro/p/N82E16833320556
There's also the TP-Link BE550 which has Wi-Fi7 and five 2.5Gbe ports.
What do you recommend without breaking the bank account?
If you don't care about power consumption, look for EOL switches from datacenters. If you care about power consumption, buy multi-gig switches from AliExpress.
If I have 1 port 2.5g WAN and 2 ports 10Gb LAN
Yes, the Asus routers are flexible and you can use any of the multi-gig ports for the WAN and the rest will be LAN ports. For example the [GT-AXE16000]Imgur.
With that large temperature delta between most P-Cores and the two hot ones, my suggestion is to take a closer look at how the thermal paste is distributed over the CPU surface and see if the "pump-out" effect has caused the paste to be too thin in the middle .