Networking noob looking for help to build a vpn server

[Amd7674]

Hi,

I'm it guy and I've building my own PCs for me and my family for the last 30yrs.  However, networking has never been my strongest suite.  I can get by,  but it is always a struggle.  I can follow a guide but I always run into issues.  For my home network I'm currently using 3 x 6 pro eeros .   I've set it up about 3yrs ago and I'm happy overall. 

Recently I was thinking about purchasing a cheap vpn router and use it with Surfshark.    So I came across an idea to use  OPNsense (and help from their great community) to build vpn WireGuard router and perhaps later a full blown (dhcp, firewall etc) router and put my 6 pro eeros in a bridge mode as APs for wifi.   This project should (I hope) also help me to learn more about networking ( my Achilles heel) .

I currently have 4/5 functioning old win10 PCs and Unused 5 gigabit 5 port unmanaged switch.   My preference would be to play with my retired hardware without interrupting local network.  Later i don't mind paying for a multiple nic card if everything is working properly.
In the next few days I will try to gather my old PCs specs , CPU, Ram size, Nic card brand and hopefully you will help me to pick best one for this project :-)

First  I would like to attempt to build a vpn WireGuard router that I can plug it in into my existing network and be able to have any device on my network to use WireGuard vpn as client.

 For this do I need a PC with 2 Ethernet ports/nics or one would be sufficient ? Any beginner setup guides to help me going? 

Any help would be greatly appreciated and thank you in advance for your help!!!

[Amd7674]

The two PCs I can use are:
CPU Intel Pentium G4500 @ 3.50GHz
RAM 8GB DDR 1066 Mhz
Intel Ethernet I219-V

CPU Intel i3450 @ 3.10Ghz
RAM 8GB DDR3 1600 Mhz
Realtek controller 8111f controller <- is this nic supported?

I believe older i3450 ivybridge is about 10% faster.   Would either system be able to do vpn wireguard?

Also do I need second nic card?

[Amd7674]

Anyone?