@edstiles
When it comes to throughput estimates, there's no such thing as "VPN". Different VPN systems work differently and want different things from a processor.
Specifically,
OpenVPN runs single-threaded and relies on AES encryption, so the throughput is determined by processor speed and availability of AES-NI support on the processor. With an N100, I would surmise you can get Gigabit OpenVPN. Note, however, that OpenVPN is transitioning to multi-threaded operation, and when that happens, old limitations will no longer stand in the way.
Wireguard runs multi-threaded and can live without AES-NI support (it uses ChaCha20 by default). So the throughput is determined solely by available processor bandwidth, with an adjustment for possible cooling issues. My personal quick-and-dirty (I repeat, quick-and-dirty) guesstimation (I repeat, guesstimation) rule is, 6 GHz of processor bandwidth per Gbps of throughput, to be adjusted upward if there are cooling issues.
IPsec, as a first approximation, has computational requirements similar to Wireguard.